386 THE VOYAGE OF H.M.S. CHALLENGER. 



The first pair of gnathopoda (h) is robust, long, and pediforin, terminating in a short, 

 reversely curved and obtusely pointed stout dactylos. 



The second pair (i) is long, slender, and feeble, terminating in a long, straight, slender 

 dactylos, bordered with long hairs. 



The first pair of pereiopoda (k) is rather short and generally feeble ; it is six-jointed, 

 the dactylos apparently being absent. The propodos is long, slender, and bordered with 

 long articulated hairs, and near its articulation with the carpos there is a fasciculus of 

 serrate hairs or sj)ines mounted on a tubercle which corresponds with another on the 

 adjacent portion of the carpos, and together forming a feeble prehensile organ. The 

 meros is long and the ischium short. 



The two succeeding pairs (I, to) are longer than the others ; the two penultimate 

 joints represent the carpos and propodos, and are slender, long, and terminate in a 

 microscopically minute but perfect chela. 



The fourth pair («) is one-fourth shorter than the preceding ; the terminal joints are 

 broken off in our specimen. 



The fifth pair (o) is short, six-jointed, and feeble, it is half the length of the second and 



third, and furnished with a few long hairs. 



The branchiae consist of a podobranchial plume attached to the small or rudimentary 



mastigobranchial plate belonging to the first pair of gnathopoda ; a pleurobranchial 



plume, with an interstitial foliaceous plate, attached to the three next somites, and two 



well-developed plumes attached to the two succeeding somites. The branchial formula 



is represented in the annexed table. 



Pleurotiranchise, . . .... 1' 1' 1' 2 2 



Arthrobrancliia?, . . . 



Podobrancliia?, . . . 1 



Mastigobranchia?, . . . 1 



hi k 1 in n o 



The first pair of pleopoda is long, single-branched, and in the adult male carries a 

 large petasma which is hooked in the median line to its fellow of the opposite side. 



The second pair carries a small, pointed, scale-like appendage attached to the base of 

 the inner branch, and tipped with a few short spines. The anterior two pair's are 

 long and slender, the succeeding three are robust and short. The posterior pair forms 

 the outer plates of the rhipidura, the telson being only half their length. 



Length (male), 38 mm. (1*5 in.). 



Habitat.— Station 236, June 5, 1875 ; lat. 34° 58' K, long. 139° 29' E.; off Japan; 

 depth, 775 fathoms; bottom, green mud; bottom temperature, 37°'6. One specimen, 

 male. Trawled. 



This species resembles Sergestes cornittus, Kroyer, from which, however, it differs in 

 not having a small tooth on the dorsal surface of the rostrum, although there is an eminence 



