CAM BAR US. 13 



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

 regards both internal and external organs. 



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 be taken as positive. Similar open- 

 ings were seen also in the third pair of legs of male Parastacus piUmanus and 

 P. Brasiliensisj 



Among the vast number of Astacida) 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. propinquus, var. Santornii Faxon, GO milli- 

 meters long (M. C. Z., No. 3350). 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. jiroj'/i/'jtnts, var. Sanbornii. 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 female. 



The third specimen is a C. Diogenes 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 



* Sitzungsber. Gesellsch. naturforsch. Frouiule zu Berlin, IS Jan., 1S70. 



t E. Rousseau and E. Dcsmarest (Ann. Soc. Ent. de France, 2 e Serie, Tom. VI. p. 470, PL XIII., Tom. 

 VI. p. 4S1, 1848) have recorded cases of As/itf/m Jlaoin/ilix with two pairs of sexual orifices, one on the 

 third, the other on the fourth pair of legs; but in these specimens both pairs of orifices were vulva' leading 

 to the ovaries by a branched duct OH each side of (lie body. 



