FA UNA OF MA MMO TH CA VE—HA Y. 231 



disturbed they would remain in this position for several minutes, and 

 then with no apparent reason start off at a rapid gait, move to another 

 spot, and take up the same position. While thus resting, the only 

 movement ol)serva])le was a slight waving to and fro of the antenna. 

 Sometimes an individual was seen on a submerged rock mass resting 

 in the same way; such individuals appeared to have no difficulty in 

 running rapidly over the rough surfaces. When alarmed in any way, 

 the crayfish would begin to show signs of uneasiness by moving 

 slightly about in various directions, and then dart away, propelled l)y 

 the vigorous strokes of its tail fin. There seemed to be no al)ility on, 

 the part of the animal to select a safe haven of refuge from a distance, 

 for the fiight for safety was apt to end anywhere; the course was 

 usually laid for deeper water, but if a rock or the wall of the pool was 

 encountered the crayfish would quickly conceal itself in a crevice and 

 retreat l)eyond reach of danger. Several individuals, when repeatedly 

 chased across a small pool, became either too exhausted or too enraged 

 to retreat and showed a readiness to fight by rising high on the front 

 walking legs and waving their chelre about in the direction of the dan- 

 ger. Their movements were very quick, probably more rapid than 

 those of outside species, and it was difficult to touch their antennie 

 and escape a nip from their chelre. 



Several specimens were obtained from places where the pools were 

 nearly or quite dried up, and it was observed that in such places the 

 crayfish had dug for itself a hole or had crawled under a stone and 

 was making preparations to remain. They were already in a semi- 

 dormant condition and in a few days would doubtless have died. The 

 tracks of a cave rat, several excavations made by him, and the remains 

 of a crayfish showed that even in the fastnesses of their subterranean 

 home the crayfishes have enemies to which they sometimes fall victims. 

 It has frequently been stated that disturbing the surface of the 

 water is sufficient to frighten the crayfish. I did not find this to be the 

 case unless the disturl)ance was great enough to affect not only the 

 surface but the depths of the pool as well. Indeed I have often passed 

 my hand completely around an individual, all ready and alert, and have 

 brought my fingers within half an inch of its body without causing it 

 to show further alarm. The instant it was actually touched either on 

 its long, waving antenna^ or on any portion of its body it would dart 



awav. • I • 



From all the evidence which could be gathered it seems that m this 

 creature the senses of sight and hearing have entirely disappeared. 



At the time of these investigations the interesting article ])y Prentiss/ 

 on the otocysts of the crustacea was unknown to me and I was not led 

 to repeat his experiments on the blind crayfish. So far as I am able 

 to determine without careful microscopic examination the otocyst^f 



iC. W. Prentiss. The Octocyst of Decapod Crustacea; Its Structure, Development, 

 and Functions. Bull. Mus. Conip. Zo.",]., XXXVI, No. 7. July, IWl. 



