BATRACHIA. 313 



processes, with a greater or less degree of atrophy of the fimbriae. These animals 

 occupied holes the size and shape of their bodies, excavated vertically in the sand, 

 from which their heads protruded. They were so situated as to be overflowed by 

 every slight change of level of the water, which also kept their holes full. This 

 situation was especially adapted to a state of transition from a branchial to a pulmo- 

 nary respiration. 



Next to the A. conspersum, the slender, gray A. microstomtim is the smallest species 

 of the genus. It is common in the Mississippi valley. The A. talpoideum is found 

 in the forests of the South Atlantic and Gulf states. It is a robust and dark-colored 

 species. The most brightly colored species is the A. epixanthum of the northern 

 Rocky mountains, while the largest species, except the A. tenebrosum, is the A. aterri- 

 mum of the northern cascades of Washington Territory. The four remaining genera 

 are found in Siberia and eastern Asia. 



The Plethodontid^ are distinguished from the Amblystomidse by the presence of 

 one or two laminae on the parasphenoid bone, which are covered by a close brush of 

 teeth which look downwards on the roof of the mouth. There is considerable variety 



Fig. 181. — Amhlystoma punctatum, spotted salamander. 



of Structural character in this family. There are two principal divisions, distin- 

 guished by the form of the tongue. In the Plethodontinae, that organ is bound to 

 the floor of the mouth by the front border as well as the middle, while in the Speler- 

 pinffi, it is attached by the median pedicle only, so as to resemble a mushroom in 

 form. In these, this organ can be thrust more completely from the mouth in the cap- 

 ture of food, than in the other genera. In both divisions are genera with a reduced 

 number of digits on the anterior foot ; there being but four instead of five in JBatrco- 

 choseps, and in Manculus. The PUthodon cinereus is the smallest and the most abun- 

 dant salamander of the eastern United States. It is found everywhere in the woods, 

 under bark, logs, or stones, in comparatively dry places. The variety erythronotus is 

 very common, and is distinguished by the presence of a red dorsal band. Its habits 

 are nocturnal, and it is a great climber. They will ascend the rhachis of a fern or 

 spear of grass, scarcely strong enough to support the weight, and will lie in a coil on 

 its apex, at a height of a foot or eighteen inches above the ground. They climb a 

 plate of glass with ease, by adhering closely to its surface with their moist abdomen. 

 When disturbed on some high perch among the herbage, they leap away by a sudden 

 unbending of the coiled body, in the manner of some caterpillars. 



The Plethodon glutinosus is most abundant in the northern states and in the 

 Alleghany mountains. It is black with bluish white speckles. The P. croceater is 

 black with large orange spots, and lives in the southern Sierra Nevadas. The P. 



