X.] THE COMMON FROG. I53 



Outside the Frogs' own class, the differences may 

 be tabulated as follows : — 



The Frog differs from the entire class of FISHES in 

 the following points : — 



1. It has a skeleton, the appendicular parts of 



which are divided into upper arm, fore-arm 

 and hand, and thigh, leg, and foot, respec- 

 tively. 



2. Its hyoid, when adult, has but one pair of 



cornua instead of several branchial arches. 



3. Its skull is bony, yet devoid of a basi-occipital 



bone. 



4. It has a pelvis formed of ilia, ischia, and pubes. 



5. Its coccygeal region is rudimentary. 



6. Its skin is devoid of scales. 



7. Its limb-muscles are numerous and complex. 



8. Its nostrils open posteriorly within the mouth. 



9. The ear is provided with Eustachian tubes. 



10. The tongue is large, fleshy, and free behind. 



1 1. The adult is devoid of gills. 



12. It has a larynx. 



13. It has lungs with a pulmonary circulation. 



14. It has no fin rays. 



15. It has no tail — in the adult. 



The Frog differs from all REPTILES in that— 



1. The skull has no basi-occipital bone, while it 



at the same time has a large paraphenoid. 



2. There are two occipital condyles. 



3. Two of the tarsal bones are greatly elongated. 



