100 A REVISION OF THE ASTACID^. 



much less developed in the females and second-form males than in first- 

 form males. In some, especially young, specimens slight ante-apical teeth 

 are present on the rostrum. 



I am indebted to Mr. C. L. Herrick for three examples, two first-form 

 males and one female, of his C. signifer. It does not difier specifically from 

 Hagen's C. immunis. The antennal scale is a little broader than in the types 

 from Illinois, and the anterior process of the epistoma is not so clearly trun- 

 cated ; the punctation of the carapace is more pronounced. These differ- 

 ences are no greater than we often find in the same species when specimens 

 from widely sepai'ated localities are compared. The color, as given by Her- 

 rick, is ••■ reddish (crimson) brown, not obviously figured; tail lighter; fin 

 chestnut, marked with gray ; chelfB bright crimson below ; there are green 

 markings on the body and legs, and some yellow below." In the female, 

 the " abdomen is marked with chestnut bars on each segment above." " The 

 young males have the chete greenish blue and mottled, while the coloration 

 of the body is like the females." The figure of the antennal scale (fig. 7, b) 

 in Ilerrick's paper is very incorrect. 



The hand of this species figured by Hagen on Plate VIII. of his Mono- 

 graph is not of the normal form, but belongs to the specimen from Hunts- 

 ville, Ala., mentioned on page 72. Although this specimen is a first-form 

 male, the tufts of cilia on the second pair of legs are hardly developed. 

 The female from Beaufort, N. C, (M. C. Z., No. 3356,) doubtfully assigned 

 to this species by Hagen, does not belong here. It is perhaps C. Diogenes. 



I have seen a few specimens of C. immunis with the internal margin of 

 the movable finger straight, without the excision at the base, but such cases 

 are very rare. 



In the typical form of C. immunis the margins of the rostrum are sinu- 

 ate at the apex, without spines at the base of the acumen. In many of the 

 well-gi'own second-form males and females from the Detroit River, small 

 lateral spines are developed at the base of the acumen ; and these speci- 

 mens thus lead to a form from Obion Co., Tenn., (Coll. U. S. Nat. Mus.,) in 

 which the lateral rostral spines are developed in all the examples exam- 

 ined (seven second-form males, nine females). The sides of the rostrum 

 in some of these are neai'ly parallel as far as the lateral spines. Although 

 these specimens are of moderate size, they show the marks of innnaturity, 

 the chelipeds being small, the chelte narrow, Avith slender fingers. The inner 

 finger is generally excised at the base, as in the typical form ; the lateral 



