102 SPECIAL CONVERGENCE 



whether any of the other characters are trace- 

 able to direct genetic affinity ; and Gadow 1 

 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- 

 stomatidae, on the one hand, and their systematic 

 position under the arciferous Bufonidae, on the 

 other. The vertical pupil of the eye is an 

 exceptional character among the Bufonidae. 



TABLE OF CONVERGENCE IN BUFONID^. 

 MYOBATRACHUS. RHINOPHRYNUS. 



1. 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," Camb. Nat. Hist., 

 1901, pp. 166 and 227. 



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



