ART. XXXIT -DESCRIPTION OF CAMiURUS COUESI, A NEW 

 SPECIES OF CRAWFISH FROM DAKOTA. 



By Thos. H. Streets, M. D., U. S. X. 



A small collection of Crustacea made by Dr. Cones in Dakota iu 1873 

 contains the following new species : — 



CRUSTACEA MACRUEA. 



Family ASTACID^. 

 CAMBARUS COUESI, n. sp. 



Eostrum broad; twice as long as broad; deeply excavated above; 

 margins nearly parallel, slightly converging anteriorly; sides grooved; 

 anterior portion in advance of the lateral teeth much produced, narrow, 

 longer than the transverse measurement at the base between the lateral 

 teeth ; point and lateral teeth acute, prominent; tips corneous. The ridge 

 on the upper surface of the carapace at the base of the rostrum on either 

 side sulcate ; externally spine at the anterior extremity prominent. Car- 

 apace subcyliudrical; superior surface smooth, punctate; sides roughly 

 granular; lateral spine long, acute ; a minute spine on anterior edge of 

 the carapace below the termination of the lateral fissure ; areola narrow 

 widening posteriorly. External antennae neatly as long as the body; 

 spine externally on first and second basal articles, that on the second 

 article small and acute; lamina longer than the rostrum, broad; apex 

 spinous ; a long, acute spine on the under surface of the basal article of 

 the internal antennae, situated above the middle on the inner edge, 

 hooked forward. Epistome broader than long ; apex truncated or con- 

 cave; sides oblique; margin straight or sinuous. External maxilli- 

 peds hairy below and internally. Abdomen smooth, sparsely punctate 

 slightly longer than the cephalo-thorax. 



Anterior feet long and slender; bands long, punctate externally, 

 smooth, and sparsely punctate internally, spiny tuberculate above; tu- 

 bercles arranged in a double row; fingers long, slender, compressed, 

 more than half the length of the hand, internally and externally punc- 

 tate, smooth, externally grooved. Movable finger spiny tuberculate on 

 the superior edge; cutting edges closely approximated, toothed, tips 

 curved, and corneous ; immovable finger bearded at the base of the 

 cutting edge internally. Carpus longer than broad, sulcate above; a 

 row of tubercles on the inner edge of the sulcus ; a stout spine on the 

 middle of the inner surface, a smaller one more posteriorly ; two spines 

 on the under surface ; the spines all long and acute ; two small, acute 

 spines on the superior surface of the arm, just behind the anterior 



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