LIFE HISTORY OF DESMOGNATHUS FUSCA. 2J5 



side of the mid-line the general gray pigmentation is interrupted 

 by a row of rather poorly defined, rounded areas of lighter color, 

 in some cases showing a slight brownish tinge. These spots are 

 somewhat irregularly arranged, usually not exactly opposite 

 each other on the two sides. The number on each side in the 

 trunk region varies from 7 to 10, and the series extends nearly 

 throughout the caudal region where it finally leaves off by a grad- 

 ual diminution in the size of the areas. 



The tail is short and shows only a slight beginning of the dorsal 

 and ventral folds which are later to form the tail fin. The gills 

 are well developed and when the specimen is placed in water, 

 they stand out conspicuously from the sides of the body. There 

 are three of these gills upon each side. They are situated upon 

 the lateral surface dorsal to the gill slits, in an oblique line, the 

 most anterior one being more ventral in position and the most 

 posterior one the more dorsal. This latter one is the longest 

 and possesses from five to seven branches some of which bend 

 conspicuously forward; the middle gill has usually five branches, 

 and the ventral one three. 



The legs, particularly the posterior ones, are stout and well 

 developed, and are longer in proportion to the length of the trunk 

 region than at any later period of development. Although the 

 quick jerky motions with which the newly hatched larvae, when 

 disturbed, propel themselves through the loose soil seem to be 

 performed with the whole body rather than with the legs, there 

 are undoubtedly slower movements of the larvae when left undis- 

 turbed, which involve the action of the legs. This greater 

 proportionate size of the hind legs is, it will be remembered, one 

 of the features distinguishing Desmognathus from Spelerpes 

 larvae, and is undoubtedly accounted for by the demands of this 

 short terrestrial period preceding the aquatic larval life; since 

 the eggs of Spelerpes develop, and the larvae hatch, in the water, 

 there is no need in this species for the early development of legs 

 as organs of locomotion. 



During the period of terrestrial life, important changes take 

 place which result in a decided transformation in the appearance 

 of the larvae. The yolk protuberance rapidly diminishes, as 

 will be seen by comparing Plate I., i to 9, so that by the time 



