MAMMALS. 563 



two metacarpal bones, but they quickly coalesce to form a single 

 bone {cannon-bone). In the horse on each side of the metacarpal 

 bone, which articulates with the single finger, there is a little bony 

 stile which descends from the carpus, but does not extend as far as 

 the finger; these two lateral bony stiles {splint-bones) are, according 

 to CuviEE, imperfect fingers, whilst Meckel regards them as meta- 

 carpal bones. The stags also have similar bones; in sheep and 

 oxen a single bone only of the kind is seen on the outside. In the 

 pachydermatous mammals (with the exception of the fossil genus 

 Anojjlotherium, which has only two) there are at least three bones 

 in the metacarpus; the elephant has five such. 



The number of fingers varies from one to five. Of the five (the 

 largest and also the normal number) the third or middle finger is 

 the most constant and commonly also the longest; this is the only 

 finger in the horse. First of all the thumb appears to be absent; 

 in many the fifth (the little) finger also disappears, and after these 

 the fourth finger. In the ruminants two fingers (the second and 

 the middle finger) are constantly present, and in these two other 

 imperfect fingers are added, which, however, are absent in the 

 camel. For other particulars respecting the number of fingers we 

 refer to the Systematic Arrangement, where it will be found recorded 

 amongst the characters of the genera. Perfect fingers have three 

 joints {phalanges), except the thumb which has only two. In the 

 whales and dolphins the number of joints of the fingers is larger, 

 especially of the second finger\ The last joint of the fingers in 

 the ungulate animals is flat beneath; its anterior margin has the 

 form of a semicircle, and the upper surface descends obliquely from 

 behind forward. In the feline genus the last joint of the fingers lias 

 a sigmoid form ; in front it is excavated like a cap, and in the middle 

 of this cavity there rises a compressed conical point. To this cone 

 the claw is adapted, of which the posterior margin is received in 

 the cap and thus firmly fixed. In walking this joint is turned 

 directly upwards, and thus the point of the claw does not touch the 

 ground. At some distance from the inferior extremity of this joint 



1 This is a conformity to reptiles, especially to the fossil genera Ichthyosaurus 

 and Phsiosaurus. In the genus Bradypus the first joint of the finger is very short 

 and soon coalesces with the ossicle of the carpus ; see CuviER Ann. du Mus. V. 

 pp. 195, 196. 



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