316 LOWER VERTEBRATES. 



ing a firm grip on the females, which they seize round the groin at the time of the 

 deposition of the eggs. 



The Pleurodelidje embraces a large number of species which are mostly inhabi- 

 tants of the Old World. Their characteristic peculiarity is the bony postfronto-squa- 

 mosal arch of the skull. In other respects they agree with the Salamandridae ; that is 

 in having ball-and-socket-jointed vertebrte, with the socket behind, and in the poste- 

 rior ]irolongation of the vomers, which support two longitudinal rows of teeth on the 

 roof of the mouth. These take the place of the parasphenoid patches of the Pleth- 

 odontidfe. In the Pleurodelid:e the tongue is never developed as in the Plethodon- 

 tidae, but is generally insignificant. 



The larger number of species of this family are embraced in the genus Biemycty- 

 lus. D. punctatus is a common European species, which is of pale colors with brown 

 spots, and which presents many dermal growths at the breeding season. The D. rvs- 

 conii of southern Eurojie is a larger form. It has a spine-like process on the tibia, and 

 a greatly prolonged cloaca at the breeding season. There are two or three sjiecies of 

 Diemyctylus in North America. The largest of these is D. torosus of California, 



Fig. 184. — (Edipus varigat^ 



where it is very common in every small stream. It has a rough skin, and is brown 

 above, and yellow below. It attains a length of six inches. The common triton of 

 the stagnant ponds and ditches of the eastern states is J), viridescens. It is pale green 

 above, and pale yellow below, with small black specks. It may or may not have some 

 small round red spots, with dark borders on the sides. It generally has three shallow 

 pits on each side of the neck, which are remnants of the old branchial fissures ; these 

 are not constant, however. This species lays one egg at a time in the axils of leaves 

 of aquatic plants. The egg has a glutinous surface, and when the leaves are pressed 

 over it by the hind legs of the female, they adhere to it, and conceal it, imtil it is 

 hatched. A well-marked variety of this species is found in woods on the ground. It 

 is bright red, has red spots, and is always of smaller size. It is the su1>species mini- 

 atus. Another strong variety or species is D. 7neridional!s from southwestern Texas. 

 It is green, with large lilack blotches. There are species of Diemyctylus in Japan and 

 China, which are generally marked with red. 



The genus Pleitrodehs is only found in southern Europe, chiefly in Spain. It is 

 characterized by the long ribs which perforate the skin on each side of the body. One 

 species, P. waltli, is known. In Siranota the postfronto-squauiosal arch is so wide 



