5. Blind species found in an artesian well in Texas 



Palaemonetes antrorum Benedict Texas Blind Shrimp 

 With functional eyes; eastern states 



Palaemonetes exilipes Stimpson Common Shrimp or Prawn 



6. With a gill on each side (under carapace) of last segment of thorax; 



sexual characters not well developed (no seminal receptacle on ventral 

 side of thorax of female; no hooks on third segments of walking legs 

 of male; first appendages of abdomen (pleopods) of male simple) ; rC' 

 stricted to the Pacific slope except for one species which extends into the 

 Yellowstone region (C. clar\ii has been introduced into California) ; 

 Subfamily Astacinae (Genus Astacus Fabricius (Potamohius Leach)) 



7. 

 No gill on last segment of thorax; sexual characters well developed (in 

 the female, a seminal receptacle, appearing as a round bony entrance, 

 on ventral side of thorax; in the male, a hook or spine on third segments 

 (counting from base of leg) of one or more pairs of walking legs; first 

 appendages of abdomen (pleopods) of male with two or more tips) ; 

 east of the Rocky Mountain region; Subfamily Camharinae (former 

 genus Carnbcinis Erichson) 11. 



7. No spine on rear of postorbital ridge 8. 

 With a spine or tubercle on rear of postorbital ridge 9. 



8. Sides of rostrum with fine serrations; Yellowstone region 



Astacus gamhelii (Girard) 

 Sides of rostrum smooth; northwest coast 

 Astacus \lamathensis Stimpson 



9. Sides of rostrum serrated 



Astacus nigrescens Stimpson 

 Sides of rostrum smooth, except for a lateral spine on each side near 

 tip 10. 



10. Distance from cervical groove to lateral spines of rostrum more than two 



times posterior section of carapace; tip of rostrum longer than distance 

 between lateral spines 



Astacus leniusculus Dana 

 Distance from cervical groove to lateral spines of rostrum about two times 

 or less posterior carapace; tip of rostrum about equal to distance be' 

 tween lateral spines 



Astacus trowhridgii Stimpson 



1 1 . First pleopod of male (of the first form) with more than two tips, or with 



the outer tip truncated and bearing several (one to three) short horny 



teeth or projections 12. 



First pleopod of male (of the first form) with two tips directed forwards 



or bent at right angles to the base 38. 



12. With a hook (spine or tubercle) on third segment of second and third 



legs (in males of the first form) ; first pleopod of male with three slender, 

 straight tips; Louisiana 



Camharellus shufeldtii (Faxon) 

 With a hook on third segment of third or of third and fourth legs (in 

 males of the first form) ; first pleopod of male not so 13. 



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