A ST ACTS. 133 



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

 the hands of nearly equal size. Judging from his figure, I b, the postcarapace 

 is also longer. Perhaps these young specimens were .!. Trowbridgii Stimpson. 



A. kriusculus is closely related to A. Trowbridgii. For the distinctions, see 

 under the latter species. 



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

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

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

 spines on the second and third segments of the antennae are prominently 

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

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

 distal ends, as in A. Trowbridgii. 



Astacus Oreganus. 



Ast s Oreganus, Randaix, Journ. Acad. Nat. Sci. Phila, VIII. 138, 11 VII L839 



tslacus Oreg , 1', K a, Zoology of New York, P.. VI., Crustacea, p 23, L844. (After Randall.) 



E M cHSO N) Arch.Naturgesch.,XILJahrg.,I.375,1846. (After Kandall.) 



barus Oreganus, Gibaxd, Proc. A,,„i. Nat. S,,i. Phila, VI. 87, 1852. I Lfter Randall No docnption.) 



Utacus Oreganus, Stimpson, Journ. Bost. Soc. Nat. Hist., VI. 195, 1857. I liter RandaU.) 



Aitacus Oreganus, IIages, 111. Cat. Mus. Con,,,. ZoSL, No. Ill p 95, IS70. (After Randall.) 



"Testa grannlata, bimaculata, fronte valde 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 front with five spines, 

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

 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." — 



Randall. 



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

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

 has since hem found. The figure given by Randall 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, tin-, three distal segments of the third maxillipeds, the antennal 

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

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

 mi „ht have added al o A. Trowbridgii and .1. leniusmlus). The drawing might well be 

 Urns explained but it is hard in make Randall's explicit mention of five s P u,e-< accord 

 with such an interpretation. 1 incline, nevertheless, to Dr. Sagen's opinion, that this 

 specimen was no other than .1. leniusculus 1 lana. The short post-carapace and long ros- 

 tl „l aC umen agree better with that species than will, A. Trowbridgii. 



* Sec Proc. Lead Na1 Sci Phila , \ 30 



