CAMBARUS. 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 Jain 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 Paraslacus pilimanus and 
P. Brasiiiensis.t 
Among the vast number of Astacidz 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. Sanbornit Faxon, 60 milli- 
meters long (M. C. Z., No. 5550). 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. propinquus, var. Sanbornii. It is 
a young specimen, only 58 millimeters in length (M. C. Z., No. 5588). 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. Freunde zu Berlin, 18 Jan., 1870. 
+ E. Rousseau and B. Desmarest (Ann. Soc. Ent. de France, 2¢ Série, Tom. VI. p. 479, Pl. XIII, Tom. 
VI. p. 481, 1848) have recorded cases of As/ucus fluviatilis 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 vulve leading 
to the ovaries by a branched duct on each side of the body, 
