154 PROF. G. B. HOWES AND W. RIDEWOOD ON [Mar. 6, 



Afjlossa. The representatives of that family retain then, in this 

 feature of their organization, a more primitive condition than do any 

 other living Anura. Further comment is needless. 



Carpale 5. — All writers have, up to the present, regarded the 

 large element marked I- as the fifth carpal. In the Di&coglossidcB, 

 Pelobatidce, and in Xenopus, this is large and distinct ; and 

 seeing that in the last-named genus the head of the 5th metacarpal 

 (5', tig. 4) is especially excavated to receive it, the above-named 

 determination would appear to be unassailable. 



In the two first- named families {Discoglossidce and Pelobatidai) 

 this element has no connection with the metacarpal, for in them there 

 runs, from the postaxial border of the 4th carpal to the epiphysial 

 cartilage of the 5th metacarpal, a ligamentous band (* figs. 5, 7, and 

 15). This structure courses ventrally to the distal face of the sup- 

 posed 5th carpal {k), excluding that from direct connection with the 

 adjacent metacarpal. 



The absolute identity of this band with the ligament in the hind 

 foot, admitted by all to represent the missing tarsalia 4 (? 5), is 

 irrefutable ; and, if argument from analogy is to be trusted, this 

 structure may justly be looked upon as a 5th carpal. If so, the 

 older determination falls to the ground, and the element k can no 

 longer be regarded as distal. We are in a position to substantiate 

 this, for the ligament in question carries, in Xenophrys, a well- 

 defined nodule of hyaline cartilage which ossifies as age advances 

 (5, fig. 16). This ligament is early differentiated, and comparison 

 of the higher forms suggests that it represents something which, in 

 them, has been lost. 



"We trust thus to have shown that the 5th carpal is practically 

 absent in the Anura as an order, but that a vestige of it exists in the 

 adults oi the Discoglossidte Siwdi Pelobatidce (in precisely those forms, 

 that is, in which we might have expected to find it), becoming 

 ossified and attaining its most full development, so far as is at present 

 known, in the genus Xenophrys. 



c. Carpale 1 and Pollex. — The pollex is, in all known Anura, 

 relatively small and unimportant. It attains its maximum length 

 in certain American Tree-Frogs {cf. Cope, 14, and Boulenger, 7, pp. 

 338, 339), and among the Cystignathidce {cf. p. 170); in other 

 forms, again, it is very short. Born says of it in Botnbinator (6, 

 p. 62), "einmal fehlte sie ganz, ein andermal waren sogar zwei 

 Phalangen vorhanden ;" Gegenbaur omits it in his well-known figure 

 of Bufo {19>, pi. i. fig. 11), while Brocchi denies its existence in 

 Hemiphractus (10, p. 16). We strongly doubt the assertion of the 

 first-named author, and we can only attribute it to the fact that he 

 relied exclusively upon microscopical sections. Small the pollex 

 may be, but absent rarely, so far as our experience goes. 



In all but some few forms the body of the pollex is in articulation 

 with a proximal cartilage, /jo i. (the "trapezium" of Ecker, 17, p. 53), 

 of somewhat variable character. In its predominant shape, this 

 element may be fitly compared with the bowl of a very thick spoon. 



