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 Heptiles, to which may be added on each side a 

 peculiar symphyseal {sy) . 



The number of presacral vertebree (u) is normally eight j 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 last two, the centra are proccelous or concavo-convex. 

 The coccyx or urostyle (c) is a long styliform bone, usually 

 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 o{ precoracoids 

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

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

 [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 



Fiff. 24. 



Sternal apparatus oi Leptodactyhts pentadaetylus. 



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 



