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JOURNAL OF MAMMALOGY 
highly specialized now in existence. It is, as I have said, not known outside of 
the restricted subgenus or genus Cams. Dogs which were certainly not carried 
by modern Europeans accompany native man in many parts of the world, Africa, 
Malaya, Australia and South America, for instance, where no true Canis is known 
to occur now or to have occurred in the past, and all of them apparently retain 
these generic or subgeneric characters uncontaminated by those of their local 
relatives with which they have been brought in contact. The best explanation 
of all these conditions seems to be that dogs were originally domesticated some- 
where within the northern area inhabited by true Canis, and that they were sub- 
sequently taken by man to most of the regions into which he has penetrated. 
Wherever dogs and wild Canis in the restricted sense occur together crossing 
may take place, and by this process many, possibly all, local forms of the wolf 
have perhaps contributed to the peculiarities of domestic races. At present, 
however, there seems to be no satisfactory evidence of polyphyletic origin of any 
other kind. 
—G. S. Miller. 
Neuviile, H. De l’Extinction du Mammouth. L’Anthropologie, Paris, vol. 
29, pp. 193-212, figs. 1-3. July, 1919. 
Few ideas regarding the natural history of mammals are more generally ac- 
cepted than the belief that the Siberian mammoth was specialized to withstand 
the hardships of life in a cold climate. As a result of histological study of the 
skin of two specimens in the Paris Museum Mr. Neuville, however, comes to the 
conclusion that, far from being fitted to bear extreme cold, the mammoth dis- 
appeared mainly because the peculiarities of its integument prevented this 
necessary adaptation. The skin was covered with dense fur. But the power of 
fur to resist cold and dampness depends on the presence of the oily substance 
secreted by the sebaceous glands, and these glands, as they now are in the living 
elephants, were absent. Snow, sleet and rain could penetrate such fur to the 
base and ‘Transform it into a veritable mantle of ice.’’ Other peculiarities of 
the Siberian mammoth which placed the animal at a disadvantage were the great 
size and unserviceable form of the tusks, the absence of a protective horny thick- 
ening of the epidermis, such as occurs in the living elephants, and the tendency 
of the soles, especially of the hind feet, to throw out horny excrescences which 
resembled those occasionally seen in menagerie elephants and which must have 
seriously impeded locomotion. Mammoths probably flourished in Siberia at a 
time when the forests extended to and beyond the Arctic coast. Their physical 
limitations were such that they were unable to adapt themselves to the climatic 
changes which brought on th'e recession of the forests and the establishment of 
tundra conditions. With the development of these conditions they therefore 
gradually became extinct. 
Mr. Neuville discusses many subjects that are of general interest: the use of 
the tusks in the living elephants, the establishment of the thickened horny epi- 
dermal layer of the skin through an adaptive process which was probably at first 
pathological (“the skin of the adult elephant forms a vast corneous papilloma”), 
the function of sebum and sweat, individual variation in the number of toe nails 
in elephants, the variable size attained by adult Siberian mammoths, former 
ideas regarding the causes of extinction. 
