ENGYSTOMATINAE 227 



absent, and this loss is compensated for by exceptionally strong 

 coracoids. 



On the whole, those genera are to be considered as the most 

 primitive which have undergone the fewest losses. Those with a 

 complete shoulder-girdle, with an omo- and meta-sternum and 

 with simple phalanges, are necessarily the older forms. One step 

 farther back in another direction, the possession of teeth on the 

 palate, and on the upper jaw, leads to those genera which have 

 been separated off as DYSCOPHINAE, while teeth in the lower jaw 

 constitute the GENYOPHRYNINAE. Lastly, the firmisternal type has 

 necessarily been evolved from the arciferous condition, and there the 

 two Bufonid genera Myobatraclius and Rliinophrynus, the former 

 Australian, the latter Mexican, with their narrow and scarcely 

 overlapping epicoracoid cartilages, seem to form a connecting link, 

 although their ant-eating habits, with concomitant modifications 

 in structure, may be nothing but cases of convergent evolution. 



Key to the genera : 



I. American. A. with omosternmn .... Rhinoderma, p. 228. 



B. without omosternum. 



a. Pupil horizontal. 



Precoracoids present. 



Sacrals strongly dilated. Oreophrynella. 

 moderately . Phryniscus, p. 230. 

 feebly . Brachycephalus, p. 231. 



b. Pupil vertical. 



a. Precoracoids feeble. . Hypopachus. 



/?. absent. . Engystoma, p. 231. 



c. Pupil round. Precoracoids 



present . . . Stereocy clops, p. 231. 



II. Palaeotropical. o. Pupil horizontal. 



a. Precoracoids present. 



With palatal teeth. Madagascar. 



Ehornbophryne. 

 Palate with dermal papillae. Africa. 



Brevicej)s, p. 232. 

 With palatal dermal folds. Madagascar. 



Scaphiophryne. 



\Vith serrated palatal folds. Madagascar and 

 India. Calopkryn <,<?. 



Palate smooth. New Guinea. Sphenophryne 



and Liophryne. 

 ft. Precoracoids absent. 



Malacca. . . . Phrynella, p. 233. 

 Xew Guinea . . . Mantophryne. 

 Africa Cacosternum. 



