18 NOUTU AMKKICAN BATtS II. ALLEN. 



The t(ln<i is more inconstant in form tlian tlie radins; in all it is in- 

 conipleto and is comi)osed of a i)roxinuil and a distal rudiment. The 

 proximal rudiment is free at the weak olecranon, which resembles tlu^ 

 parts in the sloth, and is continuous in most j;enera with an arched 

 rod-like shaft of uniform width, which is ossified, as a lulc, with the ra- 

 dius at about its ])roximal third, l^^xceptions are noted to this arrange- 

 meut in some of the vcspertilionine .yenera, c. //., ScofopJiihi.s and Mini- 

 02)terus, as well as in the molossinc Fromops, in which a small anchy- 

 losed olecranon unites by a filiform shaft to the i)r(>ximal third of the 

 ulna. But the ves[»ertilioiiine forms as a rule {Hnri)ioccp}ial>is not ex- 

 amined) retain a free olecranon which is continuous with a iiliform ta- 

 periui;' shaft, which ends free in the muscles of tlie forearm. (\>r}/)io- 

 rliiuKs, Xi/<'i(>i>hili(s, ('li«li)iol<)h)is arc exceptions even to this ai-range- 

 ment, for here the shaft is entirely absent, tlic rndimental lixcd olecra- 

 non constituting the entire proximal end. The tendon of the triceps 

 muscle as it is inserted into the nlna is occupied by a sesamoid bone. 

 No other animals possess a bone in this sitnation. It is either a sepa- 

 rate ossicle develoi)cd in the tendon, or the disjuncted epii)hysis of the 

 ulna. This relatively unimportant bone receives the nuiscle which 

 ah)ne exteuds the powerful forearm. The extensor carpi ulnar is — a 

 nniscle as constant in this ^Toup as in others — arises from it. All the 

 relations of the ulna., tlu'refore, are with the extensors. Thcdistal end 

 is anchylosed to the i-adius at the wrist. The form may be that of a 

 quadrate plate which is usually entii-e, though it may retain a minute 

 foramen of insulticieucy, as a rule, in the ves[»ertilionines. The plate 

 may be absent when a hook-like process directed proximally, as in mo- 

 lossiues and Aialapha; it may project nearly at right angles to shaft 

 and be conoidal, as in phyllostomincs, rhinolophines, and the genera 

 Saecoptcryx and N'ataius', or it may be absent, as in the pteropines. 



The carpus of bats exhibits sonu^. valuable characters. In all forms 

 the first row of bones is composed of two bones only — viz, a large bone 

 which constitutes the g-reater part of the row and will here receive the 

 name of the scapho lunar, and a small separate bone at the ulna border 

 of the scapho-lunar whii-h appears to be the cuneiform. 



The second row is composed of the trapezium, trai)ezoid, os magnum, 

 unciform, and pisitbrm. The os magnum and unciform always unite 

 to form a convex surface for articulation with the second row. With 

 the exception of the pisaform all these integers are easily recognized. 

 The carpus on the whole is simple, since the first, second, and third 

 metacarpal bones arc in axial articulation with trapezium, trapezoid, 

 and OS magnum, respectively, while the fourth and fifth metacarpal 

 bones articulate with the unciform. 



In pteropines the trapezium and os magnum are greatly larger than 

 are the other bones of the second row, and g'ive a i>eculiarly massive 

 appearance to the carpus when the wing is folded. The bone first 

 named is without nodosity on the palmar aspect. Wedged between 



