TAILLESS BATRACHIANS. 



35 



parasphenoid (psp), and the pterygoids (pt). On the back of the 

 skull are the exoccipitals (eo), with a condyle on either side of the 

 foramen magnum for articulation with the first vertebra ; there is 

 no basioccipital. The toothless lower jaw is composed of several 

 bones, as in the Reptiles, to which is added on each side a peculiar 

 symphyseal (sy). 



The number of presacral vertebra (v) is eight; the ninth, or 

 sacral (sv), gives attachment to the pelvis. The vertebrae possess 

 strong transverse processes but no ribs, and, save in the first 

 and sacral, the centra are proccelous or concavo-convex. The 

 coccyx (c) is a long styliform bone, articulating with the sacral 

 vertebra by a double concavity receiving the double condyles of the 

 latter. 



The pectoral arch (fig. 23) is composed of a pair of precoracoids 

 {pco) and a pair of coracoids (co) nearly parallel, and firmly con- 

 nected in the median line by a narrow cartilage, the epicoracoid 

 (eco) ; this structure of the pectoral arch is termed the " Firmi- 

 sternal," to distinguish it from the " Arciferous " type as seen in 

 many families — for instance the Toads, in which the coracoid and 



Fig. 24. 



Sternal apparatus of Leptodactylus pentaductylus. 



precoracoid on the one side are connected by an arched epicoracoid 

 cartilage overlapping that of the other side (fig. 24). In front is 

 the omosternum (ost), composed of a cartilaginous disk and a bony 



