SKELETON OF THE SERPENT. 75 



cuboid, 5, bones. Three cuneiform bones, c, cL remain 

 detached, and immediately support the three inner toes 

 and a cartilaginous appendage. The first toe, ^, and 

 second toe, n, have each a metatarsal and two phalanges ; 

 the third toe, wV, has a metatarsal and three phalanges; 

 the fourth toe, ^V, has a metatarsal and four phalanges ; 

 the fifth toe, v^ a metatarsal and three phalanges. The 

 great length and strengh of the pelvic arch, and its ap- 

 pendages, the hind-limbs, give the frog the power of exe- 

 cuting the long leaps for which it is proverbial. 



All the batrachia present this structure in common with 

 fishes, viz., that the ribs of the trunk, when present, are 

 free, consist only of " pleurapophyses," and do not en- 

 compass the thoracic-abdominal cavity. The absence of 

 unyielding osseous girdles at this part seems to relate to 

 a peculiarity of their generation, viz: the almost simul- 

 taneous ripening of the sperm-cells and ova, causing a 

 great and sudden distension of the abdomen at the breed- 

 ing period. 



OSTEOLOGY OF THE OPHIDIA, OR SERPENT 

 TRIBE. 



There are certain tropical land batrachia — the Cecili^e, 

 e. g. — in which the body is as long and slender as in ser- 

 pents, includes almost as numerous vertebrae, and is 

 devoid of all trace of limbs. But the osteology of the 

 typical Ophidian reptiles differs from that of the batra- 

 chians in the more elongated ribs ; in the distinct basi- 

 and superoccipitals ; in the superoccipitals forming part 

 of the ear-chamber ; in the basioccipital combining with 

 the exoccipital to form a single articular condyle for the 

 atlas; in the ossification of the membranous space be- 



