REPORT ON THE CRUSTACEA MACRURA. 



570 



The second pah' of gnathopoda is five-jointed. Whether the coxa carries a small 

 podobranchial plume or not I have not determined. The basis supports a two-jointed 

 ecphysis ; the ischium is long, straight, robust, and is probably combined with the 

 meros ; the carpos or penultimate joint is short and the terminal one long. 



The first and second pairs of pereiopoda are short ; the first is robust and chelate, 

 having the carpos short, and anteriorly excavate to receive the extremity of the 

 propodos, which articulates with it at the infero-distal angle. Second pair of pereiopoda 

 slender and minutely chelate ; carpos biarticulate. 



Pleopoda biramose, foliaceous, unequal. 



Telson triangular. 



I have not seen the typical species of this genus, but comparing the specimen in 

 the collection, which I have named Platybema rugosus, with de Haan's description 

 and figure of Platybema {Hii^olyte) planirostris, I consider that the two belong to 

 the same genus. Stimpson in his diagnostic description of the genus, from a specimen 

 of Platybema planirostris that he took in the Gulf of Hakodadi, near the northern 

 shores of Niphon Island, says that the anterior four pairs of pereiopoda are furnished 

 with an ecphysis (epipod), and that the carpos of the second pair of pereiopoda is 

 triarticulate. De Haan in his description says that it is annulated, but he does not so 

 figure it in his plate, but makes the carpos long, straight, and uniarticidate. This 

 appears to be also the condition of the part in Platybema rugosus when examined 

 under a low magnifying power, but under a higher one it is resolved into a biarticulate 

 condition. 



Platybema rugosus, n. sp. (PL CIV. fig. 2). 



Robust and dorsally arcuate. Carapace dorsally carinated and anteriorly produced 

 to a deep rostrum that suddenly slopes from the crest, which is armed with teeth from 

 the posterior margin of the carapace to the distal extremity of the rostrum. Pleon 

 having the anterior two somites elevated in front, the third and succeeding somites 

 smooth, excepting the sixth, which is armed with small teeth near the posterior margin. 

 Telson having the lateral and distal margins serrate. 



