i9o S .] ORTM ANN — AFFINITIES OF CAMBARUS. 119 



3. Section : C. bartoni. 



Carapace ovate, depressed, with or mostly without lateral spines. 

 Rostrum without marginal spines. Chela comparatively short and 

 broad, depressed, ovate. Areola wide or narrow, generally distinctly 

 longer than half of the anterior section of the carapace, only in one 

 case ( C. acuminatus) slightly shorter than half of the anterior section. 

 Eyes well developed. 



The four species belonging here are all closely allied to one 

 another. Their chief differences are furnished by the shape of the 

 rostrum, width and length of areola, and shape of chelae : but all 

 are built according to the same plan. 



4. Section; C. diogenes. 



Carapace ovate, compressed, without lateral spines. Rostrum 

 without marginal spines. Cheloz short and broad, depressed, ovate. 

 Areola very narrow or obliterated in the middle, always distinctly 

 longer than half of the anterior section of the carapace. Eyes well 

 developed. 



The five species belonging into this section also form a very 

 natural group. They are connected with the bartoni-section through 

 C. latimanus (chiefly its var. striatus Hay). The peculiar, com- 

 pressed shape of the carapace (and possibly other characters, as 

 shape of rostrum, narrow areola, shape of chelae) seems to be 

 closely connected with the habits : all these species (it has not 

 been reported for C. uhleri but it is likely also the case with this 

 one) are burrowing species and so-called chimney-builders. This 

 habit begins to appear in the bartoni-section : C. bartoni often, but 

 not always, makes burrows and chimneys, apparently forced to do 

 so, when the water supply of the small mountain streams, in which 

 it lives, begins to run short in dry seasons. With the species of 

 this group, this habit becomes firmly established, and they never 

 live without making burrows, having abandoned the streams and 

 brooks, and taken to swampy and springy places, generally to the 

 groundwater, where it is found at a short distance below the surface. 



The species of this section are distinguishable by the width of 

 the areola, shape of rostrum, shape of the chelae, and in some cases 

 by peculiar colors. I believe that it is the most highly specialized 

 group of the whole genus, as is indicated partly by the burrowing 

 habits, no doubt an extreme adaptation, and, in one species (C. 

 uhleri), by the adaptation to brackish and salt-water, which is 

 found in no other case in the genus. 



