116 KANSAS UNIVERSITY SCIENCE BULLETIN, 



specimens of C. pellucidus are those which have recently shed 

 their skins will not hold good, since his specimen of C. i^ellucidup; 

 was milk-white, both before and after shedding. 



Shaler ('75) concludes, from the association of C. pellucidun 

 and C. bartonii, and the light color which often characterizes 

 cave forms of the latter, that the blind species is derived from 

 the present outside form, with which it is connected by transi- 

 tions, and supposes that the cave fauna is reenforced by inter- 

 breeding'with that of the outside ! 



In connection with the study of the habits of the cave forms, 

 it is of interest to note that Leydig finds that the external 

 fiagellum of the antennule, on which are located the cones to 

 which he has ascribed an olfactory function, is composed of 

 thirty-six segments. The cones are, for the most part, confined 

 to the middle third of the fiagellum, where there are seven to 

 each segment, the number decreasing toward either end. He 

 was unable to compare other species of Camharus, but Wright 

 ('84) follows out the suggested comparison, using C. propinquus, 

 and finds that the external branch of the antennule is composed 

 of eighteen or nineteen segments, of which the distal nine alone 

 bear olfactory cones, and only five of them, the eleventh to the 

 fifteenth, have the full number of eight on each joint. From 

 this he concludes that C. pellucidus forms no exception to the 

 conclusions which had been reached concerning the greater de- 

 velopment of olfactory organs in cave-inhabiting species than 

 in those with well-developed eyes. 



Faxon ('85) discusses these results, but finds that in C. pro- 

 pinquus the number of segments in the external fiagellum may 

 be as high as thirty-five, and of these fifteen or sixteen may 

 carry olfactory organs. In C. affinis as many as thirty-three 

 segments are counted, and nineteen of these are provided with 

 olfactory setae, while a moderate-sized C. hlandingii from New 

 Jersey shows about fifty segments, twenty-nine of which are 

 provided with setse. It thus seems that Wright's conclusions 

 .are not supported by the facts. He calls attention to the 

 interesting fact that in C. pellucidus the olfactory seta? are bet- 

 ter developed than in most species of Camharus. In the speci- 

 men of C. hamulatus examined he finds thirty segments in the 

 outer fiagellum, and the olfactory setae are long, as in C. pellu- 

 cidus. 



