26 ANURA CHAP. 



preferable name. It is frequently much reduced, even absent, 

 for instance in most Bufonidae and in the Engystomatinae. 

 The posterior so-called sternal part may be termed metasternum. 

 It forms the posterior counterpart of the omosternum. It 

 is attached behind to the epicoracoidal cartilages, or fusing 

 with them forms their posterior continuation. It appears 

 mostly in the shape of a style, which is frequently ossified, and 

 broadens out behind into a cartilaginous, partly calcified blade. 

 In the Discoglossidae only it diverges backwards into two horns, 

 assuming a striking resemblance to the typical xiphisternum of 

 the Amniota. In young Anura the metasternal cartilage is 

 intimately connected with the pericardium, an indication of its 

 being derived not from ribs but from the shoulder-girdle. 



The glenoid cavity is always formed by the coracoids and by 

 the scapula, but the precoracoid often takes part in its forma- 

 tion, for instance in Bufonidae, Hylidae, and Discoglossidae. 



In the fore-limb the humerus has a crest, stronger in the males 

 than in the females ; it assumes extraordinary strength in some 

 Cystignathidae, notably in the male Leptoclactylus. Radius and 

 ulna are fused into one bone. The carpalia are originally nine 

 in number : radiale, ulnare, two centralia, and five carpalia distalia, 

 the fifth of which is reduced to a tiny nodule or to a ligamentous 

 vestige. The primitive condition still prevails in the Disco- 

 glossidae. In most of the other Anura the fourth and third 

 distal carpalia, in any case very small, fuse with the enlarged 

 ulnar centrale ; the radial centrale comes, in the Bufonidae and 

 Pelobatidae, into contact with the radius, so that the forearm 

 articulates with three elements as in the Urodela, but with this 

 difference, that the intermedium of the Urodela has been lost by 

 the Anura. There are five metacarpalia and five fingers, but 

 the elements of the first or thumb are nearly vestigial, so that 

 the pollux is reduced to one or two nodules, scarcely visible 

 externally. The normal number of the phalanges of the second 

 to fifth fingers is 2, 2, 3, 3. The distal phalanges are generally 

 straight, either pointed or expanded or with Y or T-shaped ends ; 

 but in the Hylidae, in Hylambates amongst the Eanidae, and in 

 Ceratohyla, one of the Hemiphractinae, the terminal phalanges 

 are produced into curved claws which support the adhesive 

 finger-discs. There are, however, many genera of different 

 families, which possess finger-discs and have no claw-shaped 



