CAVE SALAMANDERS— BANTA AND McATEE. 



79 



the legs are uniformly pigmented, except a few small blotches or spots. The pig- 

 mentation is not ai^ intense as in the dorsal spots. The most striking deviation is 

 found on the dorsal surface. The usual spots are present, rather smaller than in the 

 other specimens. The intervening spaces are more densely covered with pigment 

 cells than in the normal specimens, and in several places, notably the heatl, the nape, 

 and one or two places on the back, the spots seem to have "run," their closely com- 

 pacted pigment cells having been distributed in a thinner coat over a wider area and 

 form, with the similarly distributed pigment of other spots, diffuse, evenly pig- 

 mented blotches. In life the specimen suggested that the inhibitory force which 

 kept these color cells from spreading, or the positive tropism which kept them 

 together, was dissolved and the cells scattered evenly in a single layer over the sur- 

 rounding region. , The centers of distribution are still distinguishable as darker areas 

 at the margin of or in the blotches. 



The "centers of distributwn^'' are more probably the original spots 

 where the collection of pigment began. In fact all points in con- 



FiG. 2. — Melanistic spelerpes maculicaudus. (Dorsal view.) 



nection with these specimens suggest that they represent, not modified 

 adult stages but inhibited larval conditions. The lateral color pattern 

 of the Marble Cave specimen, as shown by the figure (fig. 3), could be 

 easih^ produced by the cessation of pigment aggregation at the stage 

 represented by fig. 5, Plates VIII and IX (51.7 mm.), plus the uniform 

 distribution of isolated pigment cells over the clear lateral areas, which 

 process always occurs in the ordinarv adult. On the dorsal surface 

 there are not many spots, indicating that a few of the earliest centers 

 attracted all the pigment. The diffuse condition of these blotches and 



Fig. 3.— Melanistic spelerpes maculicaudus. (Lateral view.) 



the connection of many of them with the lateral pigment band is a 

 further indication of the cessation of concentration at some larval 

 stage. The Rock House Cave specimen with its mottled pattern on 

 the sides is probably almost a copy, as far as coloration goes, of the 

 larval stage to which we have just referred. 



IDENTIFICATION OF LARV^. 



Now that we have considered in detail the color pattern of the larva? 

 of Spelerpes maGulicaudus^ and have man}" characters to identify them 

 as such, it will be of interest to know how they may be distinguished 

 from larvae of othei* species with which they may be associated. 



Sj>elerpes larvae may be easily separated from those of Arnhlystoma 

 by their more slender form. The latter always have broad heads, 



