"On Critical Periods in the History of the Earth and their Relation to Evolution and on the Quaternary as such a Period," may be found an excellent rejoinder of Professor Clarence King's lecture before the Sheffield Scientific School on the subject of "Catastrophism and Evolution."

Among the most interesting discoveries connected with these creatures is the determination by Professor Marsh* that these early mammals, birds, and reptiles had brains of diminutive proportions. He says in regard to the order Dinocerata, a group of gigantic mammals whose remains have been found in the tertiary deposits of the Rocky Mountain region, that they are the most remarkable of the many remarkable forms brought to light. The brain of these creatures was remarkable for its diminutive proportion. So small, indeed, was the brain of Dinoceras mirabile, that it could "apparently have been drawn through the neural canal of all the presacral vertebræ." In alluding to the successive disappearance of the large brutes, the cause is not difficult to find: "The small brain, highly specialized characters, and huge bulk, render them incapable of adapting themselves to new conditions, and a change of surroundings brought extinction. The existing proboscidians must soon disappear, for similar Smaller mammals, with larger brains, and more plastic structure, readily adapt themselves to their environment, and survive, or even send off new and vigorous lines. The Dinocerata, with their very diminutive brain, fixed characters, and massive frames, flourished as long as the conditions were especially favorable; but, with the first geological change, they perished, and left no descendants." Professor Marsh says that the brain of Dinoceras was in fact the most reptilian brain in any known mammal.

reasons.

Professor Cope,† in describing the brain of Coryphodon from the deposits of New Mexico, says: "The large size of the middle brain and olfactory lobes gives the brain as much the appearance of that of a lizard as of a mammal." This is one of the lowest mammalian brains known. There are others from the Lower Eocene with equally low brains as Arctocyon of Gervais and Uintatherium of Marsh. Cope believes that the type of brain of these early creatures is so distinct as to necessitate the erection of a third sub-class of equal rank with the groups Gyrencephala and Lycencephala, which he would define as the Protencephala. He shows their approximation to reptiles.

Copet refers to Gratiolet as showing that a great development of the olfactory is a character of an inferior type; in fact, the more we ascend into paleontological antiquity, the more we find that the olfactory lobes display a greater development in comparison with the cerebral hemispheres. Dr. B. G. Wilder # has shown that in the lamprey

* "American Journal of Science and Arts," vol. xxix, p. 178. "American Naturalist,” vol. xv, p. 312.

# "American Journal of Science and Arts."

"National Academy of Sciences," 1876.

the only part which can be regarded as a cerebral hemisphere lies laterad of the olfactory lobe. In Dipnoi he finds that the cerebral outgrowth is ventrad. In another paper* he says: "In either of these directions in which what may be regarded as the special organ of the mind is projected among these low or generalized forms, there would seem to be mechanical obstacles to any considerable expansion; but dorsally there is opportunity for comparatively unlimited extension, and it is in this direction that the hemispheres begin to develop in the Amphibia and attain such enormous growth in birds and mammals." How far the small brain and presumably stolid intellects brought about the extinction of the huge tertiary mammals may be better understood by the suggestions offered by Professor A. E. Verrill in a lecture at Yale College, entitled "Facts Illustrative of the Darwinian Theory." He shows what an important factor parental instinct is in the evolution of species. He regards the lack of parental care "as one of the probable causes, though usually overlooked, of the extinction of many of the large and powerful reptiles of the Mesozoic age and of the large mammals of the Tertiary." He says: "The very small size of the brain and its low organization in these early animals are now well known, and we are justified in believing that their intelligence or sagacity was correspondingly low. They were doubtless stupid and sluggish in their habits, but probably had great powers of active and passive resistance against correspondingly stupid carnivorous species. But unless the helpless young were protected by their parents, they would quickly have been destroyed; and such species might, in this way, have been rapidly exterminated whenever they came in contact with new forms of carnivorous animals, having the instinct to destroy the new-born young of mammals, and the eggs and young of oviparous reptiles. Thus it would have come about that the more intelligent forms, by the development of the parental instinct for the active protection of their young against their enemies, would have survived longest, and therefore would have transmitted this instinct, with other correlated cerebral developments, to their descendants."

Professor John Fiske, in his "Cosmic Philosophy," arrived at a similar conclusion in regard to early man. He showed that, when variations in intelligence became more important than variations in physical structure, then they were seized upon, to the relative exclusion of the latter.

The derivative theory has not only clearly revealed the fact that animals have been derived from pre-existing forms, but it shows even more clearly that organs have been evolved as well. It is difficult, in a general review of this nature, to separate clearly the two classes of facts. Professor Cope has traced the genesis of the quadritubercular "American Naturalist," vol. xxi, p. 546. "Science," vol. i, p. 303. "American Naturalist," vol. xvii, p. 407.

tooth in the mammals of the present day. He finds that the type of the superior molar tooth of the mammals of the Puerco epoch was triangular or tritubercular—that is, with two external and one internal tubercle. Of forty-one species of mammals of this epoch all but four of them had this type of tooth. He finds that this tooth exists to-day only in the insectivorous and carnivorous marsupials. In brief, he shows a gradual change taking place from the early primitive type of tooth in the gradual development of another tubercle. The same author,* in defining the characters of an ancient order of mammals, the Amblypoda, says they are the most generalized order of hoofed mammals, being intermediate in the structure of their limbs and feet between the Proboscidia, the Perissodactyla, and Artiodactyla, which fact, together with the small size of the brain, places them in antecedent relation to the latter, in a systematic sense, connecting them with the lower mammals with small and smooth brains still in existence; and in a phylogenetic sense, since they precede the other orders in time, they stand in the relation of ancestors.

Professor Cope,† in a paper read before this Association on the "Classification of the Ungulata," gives special attention to the arrangement and character of the carpal and tarsal bones. He shows that "the weaker structure of the carpus and tarsus appears first in time; that the stronger structure appeared first in the posterior limbs, and that the interlocking structure has greatly multiplied, while the linear has dwindled and mostly disappeared. Here is a direct connection between mechanical excellence and survival."

In the light of Mr. Caldwell's unquestionable determination of the oviparous character of that curious mammal, the duck-bill mole, associated with its known reptilian bearings as deduced from its skeleton and other features, the deductions of Professor Copet regarding the "Relations between the Theromorphus Reptiles and the Monotreme Mammalia" are of great interest.

In the Theromorpha are two divisions, one of which, the Pelycosauria, is limited to the Permian, and of one of this group he makes the following comparisons: "1. The relations and number of the bones of the posterior foot are those of the Mammalia much more than those of the Reptilia. 2. The relations of the astragalus and calcaneum to each other are as in the Monotreme Platypus anatinus. 3. The articulation of the fibula with both calcaneum and astragalus is as in the Monotreme order of mammals." In brief, he shows the affinity of this reptile to be with the monotremes, and that the inities are very important in the light of Mr. Caldwell's researches, and the further fact that the development of the egg is meroblastic confirms, so to speak, the reptilian affinities of the monotremes.

* Wheeler's "United States Geographical Survey," vol. iv, part ii, p. 182.

+ "Proceedings of the American Associated Antiquarian Society," vol. xxxi, p. 477. Ibid., vol. xxxiii, p. 471.

VOL. XXXII.—8

Here, then, are a series of observations by different observers from different standpoints, all telling the same story. Osteologists have long ago pointed out the reptilian affinities of the monotremes from the character of the skeleton. The anatomists in like manner have insisted upon certain reptilian characters as well as avian characters from its internal structure. A trained zoölogist now studies it on the ground, and finds it laying true eggs, a fact that had been insisted upon several times in the present century. More significant still, the study of these eggs shows that they go through a reptilian mode of development. And now the paleontologist brings to light the remains of a reptile from the Permian rocks, and again establishes the same relations.

*

In this connection the examination by Dr. Henry C. Chapman of a fetal kangaroo and its membranes is of interest. The fœtus he examined was fourteen days old. He states that it had no true placenta, and says, "If the parts in question have been truthfully described and correctly interpreted, as partly bridging over the gap between the placental and non-placental vertebrates, they supply exactly what the theory of evolution demands, and furnish, therefore, one more proof of the truth of that doctrine."

IN

THE UNHEALTHFULNESS OF BASEMENTS.+

BY W. O. STILLMAN, M. D.

many American cities basement-houses are quite the rule; and rooms, partly or almost completely below the street-level, are in common use as work and dining rooms, and occasionally for living and sleeping purposes.

A rather casual examination of the standard works, on hygiene, of Parkes, Buck, Wilson, and others, fails to reveal any condemnation of basements, though the dangers arising from damp cellars and foundations are freely discussed. A not unnatural conclusion might be that these eminent sanitarians lived in an air of such hygienic innocence. and purity that the possibility of the enormity of basement-living had not occurred to them to be reprehended.

The value of ground-space in modern cities has caused architects to plan for the occupancy of perpendicular space below as well as above the surface of the earth. In very few dwellings are the inhabitants protected from earth-damp, whether a basement or cellar intervenes. Every physician recognizes the dangers arising from damp and cold, not to specify from noxious exhalations, and unhealthy subterranean air-currents. Rheumatism, consumption, malaria, neuralgia, etc.,

"Proceedings of the Philadelphia Academy of Natural Sciences," 1881, p. 468. + From a paper read before the Albany County Medical Society, March 23, 1887.

are constantly produced by such conditions. Humanitarians and philanthropists have painted the pitiable horrors of poor wretches living in cellars and dungeons. Are not many of the modern basements practically just as objectionable and injurious as the former?

Modern basements are, first, usually damp. In a clay soil, water is frequently found standing beneath the floor. There is commonly little air-space, the floor being usually laid almost upon the ground. The ground beneath the floor is almost always moist, as far as I have observed in this locality, and this is due to the following facts: 1. It being lower than the street it receives some surface drainage; 2. It often dips far enough down to encounter subsoil saturation, or subterranean streams; 3. Because it is usually improperly drained, if drained at all; and, 4. It is often subject to the leakage of broken or defective drains, cess-pools, etc.

The modern basement is, secondly, in danger of such air contamination as would naturally occur from unimpeded communication, through porous soil, with defective drains, sewer-leaks, and the general subsoil filthiness of a city.

To guard against the undesirable conditions mentioned several things are necessary, and should doubtless be considered in building all basement-houses. First, area-ways, or air-spaces, should be constructed around the outside walls to guard against lateral dampness, and carry off the surface-drainage, which has a tendency to sink down by the outside walls to the foundations. Second, air-spaces should be allowed under basement-floors, and these should be ventilated. Third, damp-proof courses should be laid in all foundation-walls, to prevent the upward spread of moisture throughout the house. An ordinary brick will hold nearly a pint of water. A house not thus protected will always remain damp and unhealthy. Fourth, the entire surface of the ground under a basement-floor should be covered with a layer of concrete, at least six inches thick, and this in turn covered and hermetically sealed, from wall to wall, with a coating of coal-tar or Portland cement. This keeps out vermin as well as damp, and effectually shuts out dangers from leaking sewers or drains. Fifth, the foundations of a house, in a moist soil especially, should be drained. Sixth, the main soil or drainage pipes, which are frequently laid beneath city houses, should not be constructed of tile, brick, etc. With numerous joints, leaks and settlings are apt to occur. Heavy cast-iron pipes are best, as demonstrated by most recent experience.

The above precautions, if not defective, guard a basement against dampness, and also against foul air, coal-gas, effluvia from privy-wells and cess-pools, sewer-gas, and the various exhalations of a not infrequently filth-sodden soil, and it should not be forgotten that an unhealthy basement usually means an unhealthy house. Polluted air is sucked all over the house by the rise of heated air from the basement. If we must have basements to live in, such safeguards should be