44 



INTRODUCTION. 



segment to the limb, a sort of crus secondarium. This 

 is especially striking in Pelodytes, where the two 

 bones fuse, and resemble, but in length, the crus or 

 tibia-fibula. 



In the Biifonidse, Eylidse, and Banidie a calcified 

 epiphysis unites the two bones at either extremity. 

 In Bana and Bufo a small sesamoid bone is present on 

 the inner side of the proximal extremity of the tarsus. 

 A series of three or four small distal tarsals (Kg. 19) 

 intervenes between the astragalus and calcaneum and 

 the three inner metatarsals, whilst the two outer meta- 

 tarsals are directly in contact with the calcaneum. 

 The toes are five in number, with elongate meta- 

 tarsals and 2, 2, 3, 4, 3 phalanges. A rudimentary 

 inner digit, the so-called prsehallux, consists of a 



Fig. 19. 



Tarsus of — a. Bomhinator pachy2ms. B. Pelodytes punciatus. 

 C. Rana femporaria. 



metatarsal and one or two phalanges, the development 

 of which corresponds with that of the inner meta- 

 tarsal tubercle. In Bomhinator, Alijtes, and Pelodiites 

 the distal tarsals as well as the prsehallux remain 

 cartilaginous throughout life ; in Discoglossus the 

 prgehallux ossifies, but the distal tarsals remain cartila- 

 ginous. 



The following is a Synopsis of the Grenera and 

 Species, based on the osteological characters : 



I. Pr^coracoid curved, connected with the coracoid 

 by an arched (epicoracoid) cartilage over- 

 lapping its fellow (Arcifera). 



