70 FAUNA OF MAYFIELD'S CAVE. 



carapace very marked; but of a number of specimens from King's Cave 

 at Corydon, Indiana, two are decidedly smoother than the usual type, 

 even approaching C. pellucidus testii, while the others are nearly as 

 spiny as Kentucky specimens. An occasional individual from the caves 

 at Mitchell is as smooth as the average from Mayfield's Cave and some 

 individuals from Mayfield's show some tendency toward rostral spines, 

 while a single specimen taken in Mayfield's was fully as spiny as the 

 average individual from Mitchell. In the main the distinction holds, 

 but the subspecies C. pellucidus testii from Mayfield's Cave intergrades 

 with C. pellucidus from Mitchell. Farther south one finds the increase 

 in number and length of spines, together with the appearance of less 

 conspicuous characters, very marked, and one would not hesitate to say 

 specimens from Kentucky belong to a species different from those living 

 in Mayfield's Cave if intermediate forms were not known. 



Eigenman (1903, 169, footnote) says of Cambarus pellucidus from 

 the Mitchell caves: "We have found that the specimens of Cambarus 

 pellucidus from these caves have an eye structure much more degenerate 

 than specimens of the same species from Mammoth Cave." I have 

 made no examination of the structure of the eye in C. pellucidus testii, 

 but it seems probable that the greater degeneration noted in the eyes 

 of the specimens from Mitchell is also present in the individuals from 

 Mayfield's Cave and that the increase in amount of degeneration accom- 

 panies the decrease in spines so that individuals from Corydon, Indiana, 

 would have eyes intermediate between the eye of C. pellucidus from 

 Mammoth Cave and C. pellucidus from Mitchell, Indiana. 



This crayfish is usually seen quietly resting on the bottom of a pool. 

 Rarely one is observed walking slowly. When roughly disturbed it acts 

 and swims much as other crayfish do when excited; that is, it swims 

 without regard to the edge of the pool or even the direction of the 

 danger and is as likely as not to swim into one's hand or out upon the 

 bank. However, if there is a disturbance of the water and the crayfish 

 becomes aware of the pursuer while at a distance or before being 

 touched, it, in nearly every case, swims or crawls toward protecting 

 rocks shelving over the edge of the pool, or to some other such means 

 of concealment. If there is no such protection it moves toward the 

 opposite side of the pool. It occasionally retreats to a hole under a rock. 

 C. bartoni is quite often found in such holes. Possibly C. bartoni alone 

 forms these holes and C. pellucidus makes use of them when deserted 

 by C. bartoni. Often when slightly disturbed by an object close at 

 hand C. pellucidus backs off, then turns around, and crawls forward. 

 However, when disturbed it usually starts to swim immediately. If 

 crowded when crawling forward toward a place of concealment, it begins 



