154 THE COMMON FROG. [chap. 



4. The acetabula are closely applied, and that 



there is an iliac symphysis. 



5. The bones of the fore-arm and those of the leg 



are anchylosed together respectively. 



6. There is no distinct atlas vertebra. 



7. The coccygeal region is formed by ossification 



of the sheath of the notochord. 



8. There is no femoro-caudal muscle even in the 



young — when the tail is long. 



9. The tongue is free behind. 



10. The skin is devoid of horny scales. 

 IT. Development takes place through a metamor- 

 phosis. 



12. Gills exist in the young. 



13. The ureters open into the oviducts. 



The Frog differs from all BIRDS in that— 



1. Its blood is cold. 



2. The skull has no basi-occipital. 



3. It has two occipital condyles. 



4. It has a large paraphenoid. 



5. It is provided with teeth. 



6. The hand has four fingers. 



7. The foot has five toes. 



8. The iliac bones articulate with but one vertebra. 



9. There is an iliac symphysis and the acetabula 



are closely applied together. 

 10. The fore-arm bones are anchylosed together. 

 1 I. The leg bones are anchylosed together. 



12. Two of the tarsal bones are greatly elongated. 



1 3. There is no distinct atlas vertebra. 



