CAMBAEUS. 13 



this specimen the right half of the body was female, the left half male, as 

 regards both internal and external org;ins. 



Von Martens* has given an account of three specimens of a Cheraps with 

 openings in the basal segment of the third pair of legs (the position of the 

 sexual apertures of the normal female) co-existing with the male orifices 

 in the first segment of the fifth pair of legs. No ovary or duct leading to 

 the openings in the third pair of legs was detected ; but as the specimens 

 had lain in alcohol some seven years, the evidence against the existence 

 of any internal female organs cannot l^e taken as positive. Similar open- 

 ings were seen also in the third pair of legs of male Pamsiacus jjUimanus and 

 P. Brasiliensis.^ 



Among the vast number of Astacidaj that passed through my hands in 

 the preparation of this memoir, I have noted four specimens, all of them 

 Cambari, that combine external structures of the two sexes. 



The first is a specimen of C. propinqnus, var. Sanhornii Faxon, 60 milli- 

 meters long (M. C. Z., No. 3.350). The general shape of the body with its 

 broad abdomen, and the form of the claw, are as in the female ; there are 

 no hooks on the third pair of legs ; the appendages of the first and second 

 abdominal somites agree with those of the female, and there is a well- 

 formed, though not prominent, annulus ventralis ; the external opening of 

 the generative system, on the contrary, is situated upon a small papilla at 

 the base of the fifth pair of legs, exactly as in the male sex. 



The second specimen also belongs to C. propinqmis, var. Sanhornii. It is 

 a young specimen, only 38 millimeters in length (M. C. Z., No. 3588). The 

 first abdominal appendages are formed as in all young males of this species, 

 but the sexual apertures are situate on the basal segment of the third pair 

 of legs, and have the same appearance as in the normal female ; there is 

 also a well-formed annulus ventralis, and there are no tubercles on the third 

 segment of the third pair of legs. The second pair of abdominal appen- 

 dages are not at all transformed, but agree with the same appendages of 

 the normal feuiaie. 



The third specimen is a C. Diofjcnes Girard, from New Orleans, La., 84 

 millimeters long (M. C. Z., No. 242). It has all the external characters of 

 the female, excepting the first pair of abdominal appendages, which are 



* Sitzungsbcr. Goscllsch. iiatiirforsch. Freiiiidc zu Berlin, IS Jan., 1S70. 



+ E. Rousseau and E. Dcsniavpst (.Vnn. Soc. Ent. de France, 2^ Serie, Tom. VI. p. 170, PI- XIII., Turn. 

 VI. p. 4S1, 18iS) have recorded eases of Axliicits Jluviatilm witli two pairs of sexual oriliccs, one on tlic 

 third, the other on the I'ourlh pair of legs; but in these specimens both pairs of orifices were vulvae leading 

 to the ovaries by a branched duct on each side of the body. 



I r I'i 



