HARRIS : CRAYFISHES GENUS CAMBARUS. 67 



About a dozen cases were observed in the laboratory by Mr. 

 Andrews. The entire process lasted from two to ten hours and 

 might be repeated by either animal with some other. The two 

 were so firmly united that it was perfectly easy to transfer them 

 from one dish of water to another to examine the more minute 

 details of the process with a hand lens. By throwing the ani- 

 mals into actively boiling water for a few moments he found it 

 possible to fix them in their natural position, in which they 

 may then be preserved indefinitely. 



Shufeldt ('98) gives a figure of a pair of conjugating C. af- 

 finis. The figure much resembles those given by Andrews. 

 Through the courtesy of Doctor Shufeldt, the figure is repro- 

 duced in plate I. 



LIST OF SPECIES. 



Cambarus acherontis Lonnberg. 



8. Florida. 



1, Lake Brantley, Orange county. (Lonnberg, '94.) 



2. Gum Cave, Citrus county. (F., '98.) 



This species was described by Doctor Lonnberg ('94) from 

 Orange county, Florida. In digging a well, a subterranean rivu- 

 let was struck at a depth of about forty-two feet, after passing 

 through sand and clay, and finally five feet of phosphate rock, 

 bones and teeth of sharks, and a thin layer of hard limestone. 

 At first the crayfish were quite numerous, but later, when Doc- 

 tor Lonnberg visited the place, only the two types could be 

 found. 



Doctor Lonnberg considers that the age of the subterranean 

 rivulet in which the crayfishes were found is probably Post- 

 Pliocene or still younger. He considers the other caves in 

 which blind Cambari have been found comparatively much 

 older, and so thinks it is at least possible that C. pellucidus and 

 C. hamulatus have a much greater phylogenetic age than C. 

 acherontis. 



The subterranean water-system of Florida must be. Doctor 

 Lonnberg thinks, quite extensive. The ancestors of this spe- 

 cies — probably C. clarkii — may have forced their way into the 

 rivulet from its exterior mouth, or have more probably fallen 

 in when one of the numerous sink-holes of the region was 

 formed. 



