ASTACUS. 133 



in young specimens the posterior spines of the carapace are obsolescent and 

 the hands of nearly equal size. Judging from his figure, 1 h, the postcarapace 

 is also longer. Perhaps these young specimens were A. Trowhridijii Stimpson. 



A. Icniusciihis is closely related to A. Tfoiohndyii. For the distinctions, see 

 under the latter species. 



The posterior margin of the anterior segment of the telson is bi- or tri- 

 spinous on each side. The cone at the orifice of the green gland (" auditory 

 tubercle ") terminates in a sharp spinule ; in A. Trowhridcjil it is blunt. The 

 spines on the second and third segments of the antenna} are prominently 

 developed and acute. The anterior process of tlie epistoma is triangular, 

 similar in form to that of A. Trowhridgli. The fingers are spinulose at the 

 distal ends, as in A- Trowhridgii. 



Astacus Oreganus. 



Astacus Oreganus, Kandall, Joiirn. Acad. Nat. Sci. Phila., VIII. 138, PI. VII., 1839. H / 5 M c ] 



Jstacas Oreganus, De Kay, Zoology of New York, Pt. VI., Crustacea, ]i. 23, 1S44'. (After Raudall.) 



Astacus Oreganus, Erichson, Arch. Naturgescli., XII. Jahrg., I. 375, 18JG. (After Kandall.) 



Gamburtts Oreganus, Girakd, Proc. Acad. Nat. Sci. Phila., VI. 87, 18.')2. (After JIaudall. No desci'iptiou.) 



Astacus Oreganus, Stimpson, Jourii. Post. Soc. Nat. Hist., VI. 495, 1857. (After Kandall.) 



Astacus Oreganus, Hagen, 111. Cat. Mus. Comp. ZooL, No. III. p. ^i'^i, 1870. (After Randall.) 



"Testa granulata, bhnacnlatii, fi'oiite vakle producta. 



" Body fuscous, granulated, carpus with a sharp spine at the inner angle ; arm pro- 

 duced into a spine on each side anteriorly ; thorax behind the fi-ont with five spines, 

 placed three before and one on each .side behind the lateral ones ; a large reddish sjoot 

 on each side posteriorly ; front little reflexed on the sides, terminating in a very long 

 slender spine, and having a short marginal spine on each side. 



" Length about four inches. 



"Taken by Mr. Nuttall in the Columbia River, west coast of North America." — 

 Eandall. 



The type of A. Oreganus was lost or destroyed while in the hands of the artist by 

 whom the drawing was made,* and no specimen answering to the description and figure 

 has since been found. The figure given by Eandall is very faulty, as has been pointed 

 out by Hagen. The tri-articulate structures interpreted by Hagen as badly drawn anten- 

 nal scales are, I think, tlie tliree distal segments of the tliird maxillipeds, the antennal 

 .scale not being represented at all. Dr. Hagen thinks that the median spine at the base 

 of the rostrum may be a carinated elevation simply, such as is seen in A. nigrcsccns (he 

 might have added also A. Troichridfjii and A. Icniusculus). The drawing miglit well be 

 tluis explained^ but it is liard to make Eaudall's explicit mention of five spines accord 

 with such an interpretation. I incline, nevertheless, to Dr. Hagen's opinion, that this 

 specimen was no other than A. Icniusculus Dana. The short post-carapace and long ros- 

 tral acumen agree better willi that species tlmn witli A. Trowhridgii. 



* See Proc. Acad. Nat. Sci. Phila., V. 30. 



