550 .ANURA [CH. 



dentary bone. In the frog only the premaxilla and maxilla and 

 voiner bear teeth. .Most Anura agree with the Frogs in this, but, 

 as already mentioned, the Toad, Bufo, and its allies are entirely 

 toothless (Figs. 269, 270). 



The hinder visceral arches are reduced to a still more rudimentary 

 condition than those of Molge. They are represented by a thin plate 

 of cartilage called the basilingual with short blunt processes, of 

 which only the last pair, which embrace the glottis, are ossified 

 (Fig. 271). This pair are termed the thyrohyals. The whole "hyoid" 

 is thus the remains of the visceral arches. 



The pectoral girdle is much more strongly developed than in 

 the Urodela. The coracoid and precoracoid processes are joined 

 at their inner ends by a longitudinal bar, the epicoracoid, so as to 

 enclose a space called the coracoid foramen. The two epicoracoids 



FIG. 271. Visceral arches of Amphibia. A. JRana temporaria adult. After 

 Parker. B. Tadpole of Rana. After Martin St Ange. 



In A the ossified portions are slightly shaded, while the cartilaginous 

 portions are left white. 



1. Basilingual plate. 2. Hyoid arch. 3. First branchial arch. 4. Second 

 branchial arch. 5. Third branchial arch. 6. Fourth branchial 



arch. 7. Thyrohyal = fourth branchial arch. 



are in the frog firmly united in the middle line. In many Anura 

 however they merely overlap (Fig. 272, B). 



The upper portion of the pectoral girdle is ossified by a bone 

 called the scapula. As in Urodela, however, the cartilage projects a 

 long way beyond it, and this portion is called the suprascapula and 

 <may become partially ossified. There is a distinct coracoid bone 

 ossifying the coracoid process, and the precoracoid is underlain by a 

 dermal bone called the clavicle. In front of the pectoral girdle 

 in the middle line lies a small rounded piece of cartilage called 

 the episternum, followed by a bony piece, the omosternum. 

 Behind the girdle in a similar position is a cartilaginous bar with 

 a flattened end, ensheathed by a bone called the sternum; the 

 flattened end is called the xiphis tern urn. The omosternum has 



