CHAP. IV.] THE SKELETON OF THE LIMBS. 99 



end, while in each of the other metacarpals there is an epiphysis at 

 the distal end only (Fig. 60). 



The proximal surface of the first mctacarpal is deeply concave 

 from side to side, and convex from hefore backwards, to suit the 

 saddle-shaped surface of the trapezium which supports it. 



The four other metacarpals decrease in length outwards from the 

 third, and the second is slightly shorter than the fourth, hut longer 

 than the fifth. 



The articular surfaces of the heads of the metacarpals extend 

 further on the palmar than on the dorsal aspect. 



Each on its palmar aspect has a median ridge, on each side of 

 which a small rounded ossicle, called a semmoid bone (s), is attached. 



The ulnar side of the proximal end of the fifth metacarpal 

 exhibits a slight prominence or tuberosity. 



The distal surface of the first metacarpal slopes obliquely down- 

 wards and towards the ulnar side. 



8. The toes, or DIGITS, of the fore-paw (corresponding to our 

 thumb and four fingers) have each a distinguishing name. 



Thus the first digit (thumb) is termed the pollex. 



The second is the index. 



The third is the medius, or middle digit. 



The fourth is the anmthis, or ring digit. 



The fifth is the minimm, or little digit. 



Each digit consists of three rather elongated bones termed 

 PHALANGES, except the pollex, which has but two. 



Each phalanx ossifies by an epiphysis, which is situated at its 

 proximal end (Fig. 60, p l e and p 2 e). 



The two phalanges of the pollex are of nearly equal length, 



In every other digit the phalanges become successively shorter 

 and smaller, the third phalanx being, however, but little smaller 

 than the preceding one, while it is vertically expanded to support 

 the claw. 



The phalanges of the proximal row (p l ) are somewhat curved 

 like the metacarpals. They are smooth and transversely convex 

 dorsally ; on the palmar surface they are flat or somewhat concave, 

 each lateral margin being somewhat raised. At their proximal end 

 each is concave (for the supporting metacarpal), but distally each 

 presents two condyles divided by a shallow groove. 



The middle row of phalanges (p 2 ) are like the proximal ones, 

 except that they are smaller, and that each presents at its proximal 

 end a median elevation with a concavity on each side, these con- 

 cavities joining the convexities of the proximal metacarpals. 



The penultimate phalanx of each digit, except the pollex, is 

 hollowed out on its outer (or ulnar) side, and the ultimate phalanx 

 habitually lies bent back, reposing in the cavity thus prepared 

 for it. 



Each distal phalanx (Fig. 59) has its proximal end produced back- 

 wards below, so that, when the bone is placed with its long axis 

 horizontal, its articular surface looks upwards. Beyond this 



IE 2 



