5G4 COLLECTIONS FROM THE AVESTEEN INDIAN OCEAN. 



margin of the rostrum, whereas in P. canaliculatus there is commonly 

 but one ; and it is not stated in the author's description whether the 

 terminal segment of P. brevirostris bears lateral marginal spinules. 

 As the tvpe was from llealejo, on the west coast of Nicaragua, the 

 range of P. canaliculatus (if it bo identical with that species) seems 

 to extend eastward to the American coast. 



1 may add here, that P. occidentalis, Streets*, from the Isthmus 

 of Panama, to which reference is not made in my paper above re- 

 ferred to, seems to be identical with P. stylirostris, Stimpson, which 

 I supposed (in 1878) to be synonymous with P. indicus ; but accord- 

 ing to Mr. Spence Bate, who has since examined the types in the 

 Paris collection, not only P. indicus but also P. semisulcatus, Be Haan, 

 P. carinatus, Dana, P. tahitensis, Heller, and P. esculentus, Haswell, 

 are varieties of P. monodon, Fabricius (vide Ann. & Mag. Nat. Hist, 

 eer. 5, vol. viii. p. 177, pi. xii. fig. 5, and p. 178, 1881). The designa- 

 tion P. stylirostris has precedence by a few weeks only over P. 

 occidentalis. 



8. Penseus richtersii. (Plate LII. fig. A.) 



Carapace with the cervical region scantily clothed with a short 

 pubescence. Rostrum very short, reaching about halfway to the 

 end of the eye-peduncles, ascending slightly, and laterally com- 

 pressed ; armed above with six teeth, of which the two posterior are 

 situated on the dorsal surface of the carapace, aud behind these, 

 but at no great distance, on the gastric region is another tooth ; the 

 lower margin, .under a low magnifying-power, appears entire, but is 

 very minutely denticulated ; the distal end is subacute, but not pro- 

 longed into a spine. On the carapace is an antennal and hepatic 

 spine, and also a small supraocular spine or tooth ; its dorsal sur- 

 face, behind the gastric spine, is not distinctly carinatcd. The post- 

 abdomen is smooth and nearly glabrous ; its fifth and sixth seg- 

 ments are slightly dorsally carinated, but the carina does not 

 terminate in a spine ; there is a very small spiniform tooth at the 

 postero-lateral angles of the sixth segment ; the terminal segment 

 is narrow and acuminate at its distal extremity, dorsally canalicu- 

 lated in its proximal half, with three pairs of lateral mobile spines, 

 of which the posterior pair are much longer and jointed in the 

 middle. The eye-peduncles are shaped nearly as in P. velutinus, 

 and scarcely reach to the distal end of the antepenultimate joint of 

 the antennulary peduncles, the longer of whose flagella is shorter 

 than the carapace. The peduncle of the antennas is concealed, in a 

 dorsal view, by the much longer antennal scale, which reaches 

 nearly to the distal end of the peduncle of the antennules ; the an- 

 tennal flagellum is slender and nearly naked (broken in the speci- 

 men described) ; the outer maxillipedes are short, scarcely reaching 

 to the end of the eyes. The legs present nothing remarkable; 

 there is a small spine on the second and, I think, the third joint 



* Proc. Acad. Nat. Sci. Philad. p. 242 (1871). 



