io2 SPECIAL CONVERGENCE 



whether any of the other characters are trace- 

 able to direct genetic affinity ; and Gadow ! 

 suggests that their community of habits with 

 concomitant modifications of structure may be 

 due to convergent evolution. The structural 

 features in the table given below are taken from 

 Boulenger ; 2 the feeding habits are gathered 

 from Gadow. Both of these authors note their 

 resemblance to the firmisternal family of Engy- 

 stomatidse, on the one hand, and their systematic 

 position under the arciferous Bufonidse, on the 

 other. The vertical pupil of the eye is an 

 exceptional character among the Bufonida^. 



TABLE OF CONVERGENCE IN BUFONID^. 

 Myobatrachus. Rhinophrynus. 



i. Distribution. Australia. Mexico. 



2. Shoulder girdle. Epicor- The same, except sternum 

 acoid cartilages narrow and rudimentary. 



scarcely overlapping ; no omo- 

 sternum ; sternum (or meta- 

 sternum) cartilaginous, ossified 

 or calcified on the median line. 



3. Eye. Pupil vertical. Pupil vertical. 



4. Ear. Tympanum distinct. Tympanum absent. 



5. Tongue small, elliptical, Tongue elongate, subtrian- 

 entire and free behind. gular, free in front. 



6. Fingers and toes free. Fingers free, toes webbed. 



7. Limbs very short, adapted Limbs very short, 

 for burrowing. 



8. Male with a subgular vocal Male with two lateral vocal 

 sac. sacs internal behind the angle 



of the mouth. 



9. Habits. Feeding on ter- Feeding on termites and ants, 

 mites and ants. 



1 H. Gadow, "Amphibia and Reptiles," Cam 6. Nat. Hist., 

 1901, pp. 166 and 227. 



2 G. A. Boulenger, Catalogue Batr. Sal, 1882, pp. 328-329. 



