CALIFORNIA STALK-EYED CRUSTACEA. 163 



Subtribe HOMARIDEA. 



Carapace not stronglj' compressed and furnished with a more or less 

 flattened rostrum. Antennal acicle present. First three pairs of pereo- 

 pods chelate, the first pair large; last five pairs of pereopods with seven 

 joints. Abdomen rather wide, the segments overlapping and laterally 

 produced. Tail-fin well developed. 



Family ASTACID^. 



Carapace subcylindrical; rostrum well developed. Fifth thoracic seg- 

 ment movable. First abdominal segment in the male (and generally also 

 in the female) furnished with sexual appendages. Telson and the outer 

 branch of the uropods divided by a cross furrow. 



Terrestrial or fresh water species confined to the 

 northern hemisphere. 



Genus Astacus Fahr. 



This genus is distinguished from Cambarus chiefly by the possession of 

 a pleurobranchia on the last thoracic segment. The Astacidae west of the 

 Eocky Mountains belong, without exception, to the genus Astacus, while 

 the numerous species inhabiting the Mississippi vallej'' and the eastern 

 states belong to the closely allied genus Cambarus. 



Astacus klamathensis St. 



Astacus klarriathensis Stimpson, Proc. Bost. Soc. Nat. Hist., Vol. VI, 1857, 

 p. 87; Journ. Bost. Soc. Nat. Hist., Vol. VI, 1857, p. 494. Bate in 

 Lord's Nat. in Vancouver's Is., Vol. II. 1866, p. 278. Hagen, 111. 

 Cat. Mus. Comp. Zool. Harvard Coll., No. 3, 1870, p. 93, PI. Ill, fig. 

 169. LocKiNGTON, Ann. Nat. Hist. (5), Vol. II, 1878, p. 303. Faxon, 

 - Proc. Amer.' Acad. Arts and Sci., Vol. XX, 1884, p. 151; Mem. Mus. 

 Comp. Zool. Harvard Coll., Vol. X, No. 4, 1885, p. 131, PI. VI, figs. 1 

 and 2; Proc. U. S. Nat. Mus., Vol. VIII, 1885, p. 356; lUd., Vol. XII, 

 1890, p. 634; Ibid., Vol. XX, 1898, p. 665. 



A rather small species with a smooth, punctated carapace. Rostrum not 

 so long as in Trowbridgii, with the sides converging anteriorly and the 

 dorsal surface concave and marked with an obscure median ridge; term- 

 inal tooth acuminate and shorter than in Trowbridgii; lateral teeth acute 

 or subacute and not produced into spines; a single spine on either side of 



