ASTACIDEA. 525 



but little oblong, inner margin straight, unarmed, except a short 

 spine at apex ; arm with anterior margin denticulate, and a longer 

 tooth at apex, on outer margin, short distance from apex, uni- 

 spinous. Following pairs of feet nearly naked. Caudal segment 

 sparingly oblong, sides nearly parallel. Fifth pair of feet bearing 

 small branchise. 



Plate 33, fig. 1 a, male, natural size; h, a younger individual, having 

 the two posterior spines of frontal part of carapax obsolescent. 



Columbia River and Puget's Sound. 



Length of largest specimen, four inches. ' In the younger specimen 

 the hands are nearly equal, while in the larger they are much un- 

 equal, the left being the larger. The punctulations of the surface are 

 slight impressions, each bearing one or more very short and minute 

 hairs. 



Astacus (Cambartjs) Bartonii (Fair.) j Ericlism. 



Plate 33, fig. 2 a, carapax and antennse, natural size ; h, larger 

 hand ; c, caudal segment. 



Locality uncertain ; possibly from Brazil. 



The beak is entire, and terminates in a low angle ; either side of 

 its base, along the carapax, there is a low ridge, but no spines. The 

 post-medial areolet is narrow linear, enlarging somewhat anteriorly 

 and more posteriorly — for the exhibition of which fact, and a compari- 

 son with the corresponding part in the European and Oregon species, 

 the figure of the carapax has been introduced into the Atlas. The 

 hand has its upper surface and the fingers pitted and in part small 

 tuberculate.- 



Astacus Bartonii, Fabr., Supp., p. 407 ; Say, Jour. Acad. Nat. Sci. Philad., i. 167 j 

 Harlan, Med. and Phys. Res., p. 230, plate facing p. 230, f. 3. 

 A. Cambarus Bartonii, Erichson, Arch. f. Nat., 1846, 97. 

 Astacus affinis, Edwards, Crust., ii. 332. 



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