THE ANTERIOR LIMBS. 



121 



Fi?. 81. 



3. Digital Region (Fig. 81). — Here we &n<\ five digits, eacli composed of three bony colum- 

 nettes, with tlie exception of the thiimb, ia which only the second and third phalanges are 

 present. Tliey decrease in length from the third to the first, and tiie third to the fifth. The 

 first and second phalanges are small somi-cyliudricsil hones, slightly thickened at their ex- 

 tremities. Tlie ungual phalanges are constricted in tlieir middle, and widened like a horse- 

 eiioe at their inferior extremity ; the palmar face is roughened, the dorsal face smooth. 



Article V. — The Hand in General. 



1. The limits of this ret^iou, as already mentioned, extend from the lower 

 end of the forearm to the third phalanx, inclusive. If it is examined super- 

 ficially, the differences it presents in the number and arrangement of the parts 

 composing it are very striking. The digits that 

 terminate the hand are pieces which, from the earliest 

 times, have most occupied the attention of observers. 

 Thus, when we do not go beyond simple appearances, 

 it might be believed that, with regard to the number 

 of digits, there were great differences in animals. 

 From this point of view, the domestic animals form 

 a nearly decreasing series, commencing with the Car- 

 nivoraand terminating with Solipeds. And in relying 

 upon these appearances, some anatomists have dis- 

 tinguished these animals as monodadi/les, didactyles, 

 and regular and irregular tetradacttjles ; but in the 

 generalizations in this work, we have ignored these 

 designations, as they are in complete disaccord with the 

 teachings of philosophical anatomy. In fact, although 

 the Horse appears to have only one digit, the Ox two, 

 the Pig four, the Dog and Cat live, yet the hand in all 

 these creatures may be referred to the pentadactylous 

 type. To demonstrate this unity in composition, the 

 laws promulgated by (ra-the with regard to the vege- 

 table kingdom, and de\eIoped and applied to animals 

 by Geoffroy Saint-Hilaire, are accepted ; and we have 

 indicated in these few words the laws of analogy and 

 harmony, the principle of relations, the elective affini- 

 ties, the organic adjustments. 



These laws and these principles have been more 

 particularly applied to the study of the hand of 

 animals by Joly and Lavocat, Paul Gervais, Richard 

 Owen, Delplamjue, and Arloing. Comparisons, and 

 the attentive study of normal conditions and anomalies, have served as a basis 

 for the conclusions arrived at by these authorities. The anomalies that certain 

 zoologists were tempted to regard as proper facts likely to mislead philosophical 

 anatomists, have, on the contrary, been of assistance to the latter ; because, 

 according to the expression of Geoffroy Saint-Hilaire, " an anomaly restores that 

 which we term, in zoology, normal conditions." 



2, The Archetypal Hand. The chief type is composed of five digits, 

 and a complete digit in three sections — the carpus, which has two bones ; the 

 metacarpus, which has only one ; and the phalangeal section, which has three. 

 This constitution of the hand has been conceived by Joly and Lavocat, and 

 reasoning would sanction its acceptance, if it were not presented in some animals 



PALMAR SURFACE OF LEFT 

 HUMAN HAND. 



1, Scaphoid bone; 2, semilu- 

 nare ; 3, cuneiform ; 4, pisi- 

 form ; 5, trapezium ; 6, 

 groove in trapezium for ten- 

 don of flexor carpi radialis; 

 7, trapezoides ; 8, magnum ; 

 9, unciform ; 10, 10, the 

 five metacarpal bones; 11, 



11, first row of phalanges; 



12, 12, second row; 13, 13, 

 third row; 14, first phalanx 

 of the thumb; 15, second 

 and last phalanx. 



