260 S. I. Smith — Species of Pinnixa 



The following systematic account of the two species of Pinnixa 

 above referred to gives the obvious specific characters of the adults 

 and the principal bibliography of each species. 



Pinnixa chsetopterana stimpson. 



Pinnixa cylindrica Stimpson, Annals Lyceum Nat. Hist. New York, vii, p. 68 (22) 

 1859 (partial desc. ; South Carolina, in tubes of Chcetopterus) [Non White nee 

 Say sp.) 

 Pmn/iKffl c/tcefopferrma Stimpson, op. cit., vii, p. 235 (107), 1860 (desc; syn.; same loc.) 

 Kingsley, Proc. Acad. Nat. Sci. Philadelphia, 1878, p. 324 (9), 1878 (North Car- 

 olina); op. cit.. 1879, p. 402. 1880 (Virginia, Florida). 

 Frtxon, Bulletin Mus. Comp. Zool. Cambridge, v, p. 263, pi. 4, figs. 1-4 (zoea). pi. 

 5, figs. 8, 9 (chelipeds), 1879 (Long I. Sd. and Buzzard's Bay). 



The carapax is very broad and broader in tlie males tlian in the 

 females, adult males and large females being two and a fourth times 

 as broad as long. There is a distinct and minuteh' tubercular ridge 

 along the anterior inferior edge of the branchial region just over the 

 bases of the chelipeds; and above, and neai-ly parallel with this, 

 there is a denticulated carina, or line of minute denticles, across the 

 swollen branchial region, on a line from the base of the third ambu- 

 latory leg toward the eye, but not i-eaching the lateral margin of the 

 carapax nor crossing the cervical suture, though there is a slight eleva- 

 tion on the hepatic region opposite the carina. This line of denticles 

 is better marked in the females than in the males. The transverse 

 crest upon the cardiac region is conspicuous in both sexes : in the 

 female it is marked by a slender but sharp carina interrupted for about 

 a third its length in the middle ; while in the male the carina is even 

 more broadly interrupted in the middle and projects each side in a 

 very prominent, transversely elongated, dentiform protuberance. 



In the male the chelipeds are much stouter than in the female: 

 the propodus is nearly smooth, as long as the carapax and some- 

 what swollen in the middle; the prehensile edge is terminal, but 

 projects distally considerably at the inferior angle, is nearly trans- 

 verse, and armed with a triangular tootli near the base of the dac- 

 tylus and usually with a minute one near the tip. The dactylus is 

 stout, very strongly curved and the prehensile edge is nearly or 

 quite smooth. In several of the males examined one of the chelipeds 

 is a little smaller than the other and in all respects like the chelipeds 

 of the female, but these were probably all cases of reproduced limbs. 



In the female the chelipeds are smaller and proportionally less 

 stout and more compressed than in the male; the propodus is shorter 

 than the length of the carapax, and the digital portion is oblique, 

 longer than in the male, and its tip is obliquely truncated so as to 



