OF ARTS AND SCIENCES. 151 



shows no trace of tlie deep notch described aud figured by De 

 Haan. 



57. AsTACUs (Cambaroides) Dauricus. 



Astacus Dauuricus, Pallas, Spicilegia Zoolog., Fasc. IX. p. 81. 

 1772. 



Dauurische Krehs, Herbst, Versuch Naturgesch. Krabben u. 

 Krebse, II. 42. 1796. 



Astacus leptorrhinus, Fischer, Bull. Soc. Imper. Nat. Moscou, 

 IX. 467, PL V. fig. 1. 1836. 



Astacus Dauricus, Erichson, op. cit., p. 94. 1846. 



Astacus Davuricus, Gerstfeldt, Mem. Acad. Imper. Sci. St. 

 Petersbourg, VIII. 292. 1859. 



Astacus Dauricus, Kessler, op. cit., p. 361. 1874. 



Hab. Upper portion of the basin of the Amoor River. 



58. Astacus (Cambaroides) Schrenckii. 



Astacus Schrenckii, Kessler, op. cit., p. 363. 1874. 

 Hab. Lower portion of the basin of the Amoor River. 



59. Astacus Klamathensis. 



Astacus Klamathensis, Stimpson, Proc. Bost. Soc. Nat. Hist., 

 VI. 87. Feb., 1857. — Journ. Bost. Soc. Nat. Hist., VI. 494. 

 April, 1857. 



Astacus Klamathensis, Hagen, op. cit., p. 93, PI. III. fig. 169. 

 1870. 



Hab. Oregon, Washington Terr., British Columbia (Spence 

 Bate) ; from the higher regions. 



I have examined the branchiae of A. Klamathensis, A. nir/res- 

 cens, and A. Gamhelii, of the American Astnci. In all of them 

 the branchial formula is the same as in A. fiuviatilis, there being 

 three rudimentary branchia? on each side of the thorax. In 

 A. nigrescens the two anterior ones are short, but thick. They 

 are more highly developed in A. Gambelii than in any other spe- 

 cies of Astacus examined, presenting an interesting approach in 

 structure to the perfectly developed branchia. Kach of the rudi- 

 mentary branchiai is much larger than in any other species, and is 

 jointed at a short distance from the base. At the joint there are, 

 in the intermediate pair, two short lateral filaments; in the ante- 

 rior and posterior pairs, the main stem bears one filament. 



60. Astacus leniusculus. 



Astacus leniusculus, Dana, Crust. U. S. Explor, Exped., I. 524, 

 PI. XXXIII. fig. 1. 1852. 



Astacus leniusculus, Stimpson, Journ. Bost. Soc. Nat. Hist, 

 VI. 493. 1857. 



