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



the stalk, which is not furnished with an ophthalmic tubercle. The first pair of antennae 

 (fig. lb) has the peduncle about half the dorsal length of the carapace ; the first joint is 

 broad, flat, and notched on the outer margin. The second and third are cylindrical, the 

 latter terminating in a long, multiarticulate flagellum, and a short rudimentary one. 



The second pair of antennae (fig. lc) carries a very transparent scaphocerite, reticulated 

 in appearance and not strengthened by a ridge on the outer margin. 



The specimen is much dilapidated, the gnathopoda being the only appendages of the 

 pereion that are perfect, and they present nothing of specific value. 



The branchiae consist of seven plumes, which are well developed, and correspond 

 rather with the second pair of gnathopoda and the first two pairs of pereiopoda 

 than with the more posterior appendages. With the exception of the plume which is 

 attached to the small mastigobranchial plate of the first pair of gnathopoda, and which 

 is therefore a podobranchial one, none of the plumes have any connection either with 

 the legs or with their membranous articulations. They are, therefore, pleurobranchial. 



Between the somite that supports the first pair of gnathopoda and that which carries 

 the second is a small discoidal plate attached by one extremity ; a similar organ exists 

 in the furrow between each pair of somites, as far as the antepenultimate or the one 

 pertaining to the third pair of pereiopoda ; two branchial plumes, of a somewhat im- 

 poverished character, are attached to the next or penultimate somite. The branchial 

 arrangement is tabulated in the following formula : — 



Pleurobranchife, '1 '1 '1 '1 2 



Arthrobrancbise, . . . 



PodobranchicT, . . . 1 



Mastigobranchise, . . . 1 



hit 1 m n o 



The interstitial foliaceous plate being represented by a comma. 



The plumes consist of a central stem supporting lateral branches, on each side of 

 which is a series of small, laterally compressed plates that look like scrolls upon the 

 outer surface of the plume ; these diminish posteriorly where the branchiae are less 

 characteristically developed. 



The type specimen was taken off the southern coast of Japan in about 345 fathoms of 

 water, but near a point where it suddenly dips to a thousand. 



Sergestes kroyeri, Spence Bate (PI. LXX. figs. 3, 4). 



Sergestes Kroyeri, Sp. B., Joe. tit., p. 193. 



Rostrum elevated into a short, crest-like tooth. Carapace smooth, having the visceral 

 regions well defined. Pleon laterally compressed. Telson two-thirds the length of the 

 outer ramus of the rhipidura. 



