CAMBARUS. 67 



a. iHcmtauns, the anteiniaj were longer, the rostrum was more tapering and 

 ternunated in a more elongated point, and the areola narrower. This was 

 probably a form of C Burionil, whether identical with Rafinesque's C. pii- 

 silliis or no is doubtful. 



C. rohisUis Girard, not an uncommon form in the St. Lawrence valley 

 about Lake Ontario, is so near to C. Bartonii that it is best treated as a 

 variety of that species. The differences are sufficiently pointed out by 

 Hagen on page 80 of the Monograph of the North American Astacidae. 

 They are hardly greater than in some of the varieties of C. Bartonii noticed 

 above. Both forms, C robustus and the typical C Baiionii, are found to- 

 gether in some parts of New York State. A male specimen in the collection 

 of the Academy of Natural Sciences of Philadelphia, from Ilumber Eiver, 

 Toronto, is probably one of Girard's types. There is a male specimen from 

 Decatur, 111., in the collection of the Boston Society of Natural History, and 

 two small specimens from Tennessee, Dr. Curtis, which appear to be C. ro- 

 bustus. In the Philadelphia Academy there is also a young specimen from 

 Florida that resembles G. rofmstus, but the antenna! scale is broader at the 

 tip. C. Biirtonii, var. robnsta, is also found in Virginia. I have seen speci- 

 mens 86 millimeters in length. 



The first abdominal appendage of the male C. Bartonii, var. rohusta, is 

 figured by Brocchi, Ann. Sci. Nat., 6<^ Ser., Zool. et Paleontol., IL, PI. XIII. 

 fig. 15. 



In the Report on the Crustacea of the United States Exploring Expe- 

 dition (Pt. I. p. 525, PI. XXXIII. fig. 2) Dana describes and figures as 

 Astaciis ( Gamharus) Bartonii a crayfish of uncertain locality, " possibly from 

 Brazil." It is clearly not Gambanis Bartonii, neither is it the same as the 

 Brazilian Parastacine crayfish in the Museum of the Academy of Natural 

 Sciences of Philadelphia, as Hagen suggests (p. 11). I have not been able 

 to find Dana's type in the collections of the Smithsonian Institution. 



23. Cambarus acuminatus. 



Plate III. flg. 5, Plate ^^II. figs. 6 a, 6a. 



Cambarus acuminatus, Faxos, Proc. Amer. Acad. Arts and Sci., XX. 113, 1884. 



Rostrum long, tapering, ending in a long, sharp acumen, without lateral 

 spines ; upper surface smooth, somewhat hollowed out, margins punctate, 

 ciliate, raised into low sharp crests. Post-orbital ridges with sharp anterior 



