OF ARTS AND SCIENCES. 141 



Unus Er.," and described by him (p. 86) as C. advena Le Conte, 

 is a first form male (M. C. Z., No. 232) from Charleston, S. C. 

 The distiuctions noted by Hagen, based on the presence or absence 

 of spines on the lower side of the first segment of the antennule 

 and at the end of the cervical groove, I do not find to hold good. 

 The statement that " in the larger specimens the hand is moi*e 

 sulcated beneath at the inner margin, and the carpus more spinu- 

 lose," probably refers to Le Conte's type of G. advena in the 

 Philadelphia Academy. The female in the same jar with the 

 male type above noticed differs from the male in so many respects 

 that I doubt whether Hagen has correctly referred it to the same 

 species. All the other specimens in the Museum determined as 

 C. CaroUnns by Hagen are small specimens. No. 3368, dry 

 female from Georgia, L. Agassiz, is certainly 0. advena. No. 

 3367 (1850 of Hagen), a young female, also from Georgia, re- 

 sembles C. advena in most respects, but the antennal scale is too 

 broad near the tip. No. 230, young female specimens from Mo- 

 bile, Ala., and No. 275, a very young male from the same locality, 

 appear to belong to some species allied to C Bartonii, the tips of 

 the male appendages being strongly recurved. Dr. Hagen exam- 

 ined Erichson's type, a male, form I., in Berlin, in 1870, and 

 thought it was C. Bartonii. Erichson's description, nevertheless, 

 fits the present species very well. The structure of the male ap- 

 pendages of Erichson's type would at once prove or disprove its 

 identity with C Bartonii. If it be really C. Bartonii, the species 

 under consideration must receive a new name, G. Hagenianus. 



19. Cambarus gracilis. 



Gambarus gracilis, Bundy, Bull. 111. Mus. Nat. Hist., No. I., 

 p. 5. 1876. —Trans. Wis. Acad. Sci, V. 182. 1882. — Geol. 

 Wis., Surv. 1873-1879, I. 403. 1883. 



Hab. Wisconsin, Iowa, Illinois. 



20. Cambarus Mexicanus. 



Astacus (Gambarus) Mexicanus, Erichson, Ojo. cit., p. 99. 1846. 



? Gambarus Aziecus, Saussure, Rev. et Mag. de Zool., 2^ Ser., 

 IX. 503. 1857. — Mem. Soc. Phys. Hist. Nat. Geneve, XIV. 

 460, PI. III. fig. 23. 1858. 



Gambarus Mexicanus, Hagen, op. cit., p. 84. 1870 (after 

 Erichson). 



Hab. Mexico. 



I have seen one specimen (a male) in the Philadelphia Acad- 

 emy, which agrees with Erichson's description. It comes from 



