12 ASTACID^. 



1858. Mr. H. de Saussure, in Mem. cle la Soc. Phys. de Geneve, T. 14, 

 Pars II., pp. 450-461, Tab. III. f. 21-23, gives detailed descriptions 

 and fio-ures of the three before-mentioned species. His remark, that 

 the Camharm prefer the marshes and muddy waters, is apparently not 

 of general value. Many sj)ecies of Cinnbarus, perhaps the greater part, 

 live in piu-e running Avater ; for some species it is directly stated by Dr. 

 LeConte. 



I find it impossible to separate the species described by Mr. De Saus- 

 sure from the species described by Mr. Erichson, but a judgment from 

 two descriptions (I have seen o\\\j one female) is ahvays doubtful. I 

 am not sure that the hooked legs described )jy Mr. De Saussure corre- 

 spond with those of Mr. Erichson. I think Mr. De Saussure's second and 

 third pairs of legs are the third and the fourth of Erichson, the latter 

 commencing the numbering of the legs with the great claws, Mr. De 

 Saussure beginning with the pair next after the great claws. I think 

 the Avords in the Note by C. 3Ioiifcziii)ia\ "son C. Mcxicamts en est 

 bien distinct par le troisieme article inerme de la quafritme paire des 

 pattes," is otherwise not intelligible. In C. comobn'uiis the second joint 

 of the legs is said to be hooked ; if this be not a typographic error, it 

 is a strange exception. 



C. comobrinus is not at all compared with C. Cuhcmis Erichs. ; per- 

 haps it is unknown to Mr. De Saussure. The two descriptions show no 

 difference. The lamina of the antennae, £ 21, b., has no apical external 

 spine, — perhaps an error. 



C. Jfoiifcciiiiur does not differ from C. 3fe.ricaiim, and C. Aztccus seems 

 identical Avith C. Wicgmaniu. But I confess that my materials are too 

 imperfect to decide this question. 



ON THE CONSTANCY OF THE SPECIFIC CHARACTERS 

 AMONG ASTACID^. 



The examination of the constancy of the specific characters was a 

 chief point in my labor, especially Ijecause Mr. Gerstfeldt, in his excel- 

 lent monograph concerning the fresh-water Crustacea of Europe, has 

 reduced the number of described species to only two, by proving that 

 the characters i-elied on in their separation are far from being constant. 



The exceedingly rich mass of material before me, thus far unrivalled 

 for such a labor, has permitted a very extensive and careful examina- 

 tion of the constancy of the characters. OtherAvise vicAved, it could not 

 be denied that this rich material — there being more than a hundred 

 specimens of some species — Avould rather serve to obstruct the judg- 

 ment of the Avorker. 



Dr. J. Le Conte, in his careful monograph of the Astaci of Georgia, 

 says : " Tlie shape of the rostrum and of the clielaj and the size of the 



