36 REPTILE GALLERY. 



style; posteriorly the sternum [st), similarly formed. Above the 

 scapula {sc), on the dorsal side^ is the suprascapula [ssc], partly 

 cartilaginous. The fore limbs present this peculiarity, that the ulna 

 and radius [cr) coalesce into a single bone ; the functional digits 

 number four, but there is a rudimentary thumb {po). The pelvic 

 arch also differs much from that of higher Vertebrates; the ilia (il) 

 are elongated bones set parallel to the vertebral column, and join- 

 ing posteriorly the pubis and ischium (pi), which are united into 

 a single small discoid bone. The acetabulum, or socket for the 

 reception of the head of the femur, is far removed from the sacrum. 

 In the hind limb also the tibia and fibula {tf) are united into a 

 single bone, and the two proximal elements of the tarsus (a, astra- 

 galus; ca, calcaneum) are so elongated and strong as to resemble the 

 real tibia and fibula of other animals — the Newts, for instance. 

 The toes are also much elongated, and number five, with an 

 additional ossicle (VI) on the inner side, which is regarded as a 

 rudimentary sixth toe [prfphallux) . 



The Tailless Batrachians are distributed over the whole surface 

 of the globe except the Arctic Regions, and are most abundant in 

 the tropical and subtropical zones. They are divided into two sub- 

 orders and fifteen families as follows : — 



internal ear-openings separated. 



Series A. Firmisternia^-. 



Families : — 1 . RanidcB. 2. Dendrobatida. 3. Engystomatidce. 

 4. Dyscophid(E. 5. Ceratubatrachidce. 



Series B. Arcifera *. 



Families : — 6. Cystignathida. 7. Dendrophryniscidce. 8. Bufo- 

 nidce. ^. Hylida. 10. Pelobatidce. II. Discoglossidce. 12. Am- 

 pliignaihoduntidce. 13. Hemiphractida. 



Suborder II. Aglossa, without tongue, and with a single 

 internal ear-opening. 



Families: — 14. Dactylethridce. 15. Pipidce. 



* For the meaning of this term see p. 35. 



