396 



Vertebrata. 



usually a single ossification only. Anteriorly the pelvis is prolonged 

 into a narrow, unpaired, usually Y-staped, cartilage {cartilaga 

 ypdloides. In the Anura the ilia are backwardly- directed bony 

 rods; the ischio-pubes have fused to form a compressed vertical 

 disc. The hind limb closely resembles the fore limb in 

 structure. In the Anura the tibia and fibula are fused, and the two 



Fig. 323. 



Pig. 324. 



rig. 323. Pelvis and last vertebrse of a Frog, from 

 above, a acetabnlum, c urostyle, il iKmn, ip isohio- 

 pubis, 7 — 9 vertebrae (9 sacral vertebra). — Orig. 



Fig. 324. Pelvis of the same viewed from the 

 left side, ca cartilage. The other letters as in Fig. 323. 

 —Orig. 



proximal tarsals (the third is absent) are very long and powerful. 

 The hind limb usually has five digits. 



The musculature of the body and tail, in the amphibian 

 larva, is very similar to that of Pisces; it is separated into four 



Fig. 325. Transverse section of the 

 hind end of the head of young Frog to 

 show the tympanic cavity; dia- 

 grammatic. Cartilage and bone closely 

 dotted. / tympanum (at the point 

 where the letter is situated the colu- 

 mella is attached to the tympanic 

 membrane), h brain, hy hyoid, h palato- 

 quadrate cartilage, // lower jaw, t mem- 

 branous labyrinth (quite diagram- 

 matic), 7n mouth, t tympanic cavity 

 in which the columella lies. — Orig. 



longitudinal muscle plates, each of which is divided into a series of 

 segments by thin transverse septa ; in the adult XJrodela the relations 

 are little altered, whilst in the Anura great modifications occur. The 

 brain is small, the cerebellum very little developed. 



