358 CRAYFISHES. 



son anaranjados, color fine sc observa en la parte inferior del cnerpo e inferior e interna de las pataa. 

 Estas ultimas son de color bruno-olivdceo o bien olivdceo, especialmente en las quelas."' 



With reference to the large triangular colour-patch on each side of the 

 carapace of P. bimaculatus as described by Philippi and of P. agassizii as de- 

 scribed by Porter, it should be observed that spots of the same shape and in the 

 same place are often seen in crayfishes of divers kinds shortly after they are im- 

 mersed in alcohol. These spots or blotches are the result of the quick action of 

 the alcohol on the thinnest part of the branchiostegites, which are bathed in the 

 fluid on both sides, within and without. At first red, these spots afterwards 

 fade into yellowish white, — the colour which ultimately pervades the whole 

 of the body in specimens preserved in spirits. One is almost inclined to suspect 

 that the colour-pattern noted by Philippi and Porter was due to recent immersion 

 of the specimens in alcohol. 



AsTACUS LENiuscuLus Dana. 



A large number of specimens of this species were collected for the U. S. 

 National Museum in Johnson Creek, Portland, Multnomah Co., Oregon, by 

 Messrs. Lyon and Benedict in May, 1905. The largest of these are upwards of 

 five and one half inches long and demonstrate the fact that this species has as 

 full, obese a form as .4. irowbridgii. There is considerable variation in relative 

 width of the areola in these specimens. Of twenty-six specimens, eighteen 

 (7cf , 11 9 ) have the right and left claws symmetrical, while in eight (5 cf , 3 9 ) 

 the claws are asymmetrical. In many of the asymmetrical individuals I think 

 the smaller, slenderer claw, which may be either on the right or left side, is a 

 new claw grown after the loss of the original one. 



In a male specimen collected by Mr. S. E. Meek, in Ten-Mile Lake, Florence, 

 Lane Co., Oregon, Oct. 17, 189G (U. S. N. M. No. 23,121), the chelae have the 

 form characteristic of A. leniusculus, and both pairs of post-orbital spines are 

 developed as in that species, ])ut in the shape of the rostrum and the propor- 

 tions of the areola it agrees with A . trowbridgii. Another specimen in the U. S. 

 National Museum from Astoria, Clatsop Co., Oregon, resembles A. trowbridgii in 

 the breadth and inflation of the claws and the length of the posterior section of 

 the carapace. Still another specimen in the same Museum (collected by Mr. 

 Wm. Palmer) from the base of Mt. Tamalpais, Marin Co., Cal., taken altogether 

 would be classed with .4. trowbridgii; yet in the proportions of the posterior sec- 



' Porter, op. cit., p. 258. 



