290 DE. J. &. DE MiN ON THE PODOPHTHALMOTTS 



their carpopodites are scarcely twice as long as tlie depressed 

 lanceolate dactylopodites. The last legs are nearly as long as 

 and similar to those of the fourth pair. 



The rami of the uropoda are much longer than the terminal 

 segment of the postabdomen, and are quite similar to those of 

 P. semisulcaUis. 



The largest specimen is about 20 centim. long from tip of 

 rostrum to the end of the terminal segment of the post- 

 abdomen. 



P. merguiensis differs from P. semisulcatus, de Haan, (1) by 

 the form and structure of the rostrum ; (2) by the postrostral 

 ridge not proceeding backwards to the posterior margin of the 

 carapace, and being much less distinctly sulcate ; (3) by the 

 faintly defined antennal and hepatic sulcus ; (4) by the absence 

 of the horizontal crest on the antero-iateral surface of the cephalo- 

 thorax, which in P. semisulcatus is found below and parallel to 

 the hepatic crest, being directed towards the peduncle of the 

 outer antennse ; (5) by the inner flagellum of the upper antennae 

 being shorter than tlie external one. P. merguieiisis also differs 

 from the Australian P. esculentus, Hasw., by its straight rostrum, 

 which is armed with more teeth, by the faintly defined gastro- 

 hepatic sulcus, and at first sight by the much longer internal 

 antennae. It also difi'ers from the still imperfectly known 

 P. indicus, with which P. carinatus, Dana, is probably identical, 

 by the shape of its rostrum ; by the somewhat shorter flagella 

 of the internal antennae, of which the external one seems not to 

 be dilated at base ; by the much shorter flagella of the external 

 antennae ; by the form of the ventral plate ; and probably by some 

 other characters. 



161. Penjeits Ltsianassa*, n. sp. (PI. XIX. fig. 1.) 



fourteen specimens (6 c? , 8 $ ) of this interesting new species 

 were collected in the Mergui Archipelago. 



PencEus Lysianassa belongs to that group of species in which 

 the rostrum is shorter than the eyes ; and it is apparently closely 

 allied to P. Richtersii, Miers, from the seas of Madagascar. 



The cephalothorax is scarcely more than twice as long as 

 broad, and is scantily clothed with a short pubescence; some 

 parts of the surface that are slightly elevated are quite glabrous, 



* Lysianassa, one of the Sea-nymphs. 



