90 A EEVISION OF THE ASTACID^. 



curved, costate above ; the two fingers are furnished witli blunt tubercles 

 on their opposed margins, which touch one another only at their tips. Car- 

 pus with a strong inner tooth. Third pair of legs hooked. First pair of 

 abdominal appendages stout, bifid ; rami short, acute, outer one with its tiji 

 turned outwards, inner one with its tip turned inwards ; tips brown, horny. 



Male, form II. — The fingers are less gaping, the hooks on third pair of 

 legs small, the first pair of abdominal appendages are bifid for a less distance 

 from the tip, the rami are swollen, without horny tips ; these appendages 

 may or may not be articulated near the base. 



Female. — Chela like that of the male, form II. Annidus venti-alis with 

 anterior border depressed, posterior border elevated, tuberculate, tubercle 

 divided longitudinally by a sinuous furrow^ 



Knotvn Localities. — Indiana: New Albany. Kentucky (Bundy). 



I have seen two of the types of this species, male form I. and female, 

 in the collection of the Peabody Academy of Science, Salem, Mass. Dr. 

 Sloan has also sent me specimens taken at the same time with those sent 

 to Bundy for description, and there ai'e specimens from the same source 

 in the collections of the Boston Society of Natural History, the Peabody 

 Museum of Yale College, and Butler University, Irvington, Ind. 



Dr. Sloan writes me that this is the common species in running streams 

 at New Albany, while C. Bartonii is the form found in still waters. Accord- 

 ing to the same gentleman, as quoted by Bundy, this is a burrowing species. 

 " He commences on the bank of the stream, burrows below the bed, and has 

 an opening two or more feet out in the stream, where he sits watching for 

 anything that may turn up, with a safe retreat." 



C. Sloanii closely resembles C. 2yyopinqims, var. olscnra, in general appear- 

 ance, but may be at once distinguished by the male appendages and the 

 annulus ventralis of the female. In the latter species the anterior border of 

 the annulus is prominently bituberculate, whereas in C. Sloanii the anterior 

 rim is sunk below the level of the sternum in front of it. 



The largest specimen seen by Bundy measured ^\ inches in length. The 

 largest I have seen, a female, is a little less than three inches long. 



