THE ANTERIOR LIMBS. 



121 



Fig. 81. 



3. Digital Region (Fig. 81). — Here we fiurl five digits, each compcsed of three bony colum- 

 nettes, with tlie exception of the thumb, in which only the second and third phalanges are 

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

 first and second phalanges are small semi-cylindrical bones, slightly thickened at their ex- 

 tremities. The ungual phalanges are constricted in their middle, and widened like a horse- 

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



Article V. — The Hand in General. 



1. The limits of this region, as already mentioned, extend from the lower 

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

 ficially, the diiferences 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 diiferences in animals. 

 From this point of view, the domestic animals form 

 a nearly decreasing series, commencing with the Gar- 

 ni vora and terminating with Solipeds. And in relying 

 upon these appearances, some anatomists have dis- 

 tinguished these animals as monodacti/les, didad ij.es, 

 and. regular and irregular tetradadijUs ; 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 five, yet the hand in all 

 these creatures may be referred to the pentadactylous 

 type. To demonstrate this unity in composition, the 

 laws promulgated by Grethe with regard to the vege- 

 table kingdom, and developed and applied to animals 

 by Geoff"roy 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, Delplanque, 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 \ye 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 car))i radialis; 

 7, trapezoides ; iS, 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. 



