360 CRAYFISHES. 



claws and grown them anew (see Plate 11, 12). It is interesting to note the 

 restored claws never assume the normal form but are elongated and flattened. 

 When both chelipeds have been lost and re-grown simultaneously, the result is 

 an individual with perfectly symmetrical claws on the right and left sides, so 

 different in shape from the normal claws that one might easily be led to believe 

 that it is a distinct species. Such a specimen is shown in Plate 12, fig. 2. The 

 restored claws in these cases assume an ancestral, less highly specialized from. 



ASTACUS NIGRESCENS FORTIS, Subsp. nOV. 

 Plate 7, Fig. 5, 9; Plate 9, Fig. 2. 



Similar to Astacus nigrescens, from which it is distinguished by the following 

 characters: — the sides of the rostrum converge more from the base to the tip; 

 the areola of the carapace is narrower in proportion to its length; the chelae are 

 shorter, broader, and more inflated. 



Dimensions of a male: — length, 94 mm.; length of carapace, 49 mm.; 

 width of carapace, 26 mm.; length of abdomen, 45 mm.; width of abdomen, 

 24 mm. ; length of posterior section of carapace, 19 mm. ; width of areola, G mm. ; 

 length of chela, 42 mm. ; width of chela, 19 mm. ; length of dactylus, 22 mm. 



Types:— Fa\\ River, Fall City Mills, Shasta Co., Cal., Aug. 29, 1898, 

 Rutter and Chamberlain coll., U. S. N. M., No. 44,404, 2cf , 3 9 , 1 juv. 



Paratypes: — Hat Creek, Cassel, Shasta Co., Cal., Aug. 30, 1898, Rutter 

 and Chamberlain coll., U. S. N. M., 3 9 . 



Astacus gambelii connectens, subsp. nov. 

 Plate 7, Fig. G, 10; Plate 10, Fig. 1. 



Similar to A. gamhelii (Girard), but different in these regards: — the rostrum 

 is narrower and longer, with a longer acumen, and in correlation with this the 

 antennal scales are much longer, their internal margin sloping gradually to the 

 lengthened apical spine. The post-orbital ridges, though rudimentary, as in 

 A. gambelii, develop a pair of prominent posterior spines as in ^. nigrescens, 

 while the anterior pair — the only post-orbital spines found in A . gamhelii — are 

 much more prominent than in that form. The chelae are longer and slenderer 

 than in A. gamhelii. 



Types:— V. S. N. M. No. 23,096, Snake River at Upper Salmon Falls, 

 Idaho, Oct. 3, 1894, Evermann and Scovill coll., 3cf , 1 9 . 



