. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. PACHYDERMATA. 865 In tlie Hippopotamus, the Rhinoceros, and the Tapir, the separation of the toes is more apparent externally, but still the phalanges, which are three in number to each of the four toes, are excessively strong and bulky when compared with their length. A kind of grada- tion is likewise to be traced through these genera, whereby the foot of the Elephant be- comes gradually transformed into the cloven hoof of the hog tribe, owing to the progressive diminution in size of the inner and outer toes, and the gr
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. PACHYDERMATA. 865 In tlie Hippopotamus, the Rhinoceros, and the Tapir, the separation of the toes is more apparent externally, but still the phalanges, which are three in number to each of the four toes, are excessively strong and bulky when compared with their length. A kind of grada- tion is likewise to be traced through these genera, whereby the foot of the Elephant be- comes gradually transformed into the cloven hoof of the hog tribe, owing to the progressive diminution in size of the inner and outer toes, and the gradual conversion of the terminal phalanges of the central toes into that prismatic form which adapts them to fit the horny enve- lopes that encase them like shoes. Throughout all the hog genera the weight of the body is entirely supported on the two cen- tral digits, the bones whereof are propor- tionally strong and well developed, while the phalanges of the inner and of the outer toe, which do not louch the ground, remain per- manently of very rudimentary size. Teeth.—In no order of Mammiferous ani- mals do the teeth present so much diversity of structure and irregularity of disposition as among the Pachydermatous races ; it will be therefore necessary, in adverting to this part of their economy, to describe the principal modifi- cations which the dental organs assume in different genera, before we proceed to investi- gate the manner of their formation; and this we do more willingly, because from the character and arrangement of the teeth we can alone sa- tisfactorily determine what have been the habits of extinct genera, the list of which is already considerably more extensive than that of living forms. Professor Owen, to whose labours in this department science is already so deeply in- debted, has in his recent work on the Com- parative Anatomy of the Teeth* examined this part of our subject with all the minuteness re- quired for geological researches, and from his kindne
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