REPORT ON THE CRUSTACEA MACRURA. 631 



The pleou has the anterior two somites dorsally smooth, hut a carina commences 

 abruptly at the anterior margin of the third and continues on the fourth and fifth somites, 

 and on each of these three it is posteriorly produced to a sharp tooth. The sixth 

 somite is longitudinally flat or channelled dorsally, and is furnished at the posterior 

 margin on each side of the median line with a strong tooth, and with a smaller one at the 

 postero-lateral angle. 



The telson (z) is long, tapering, dorsally channelled and has the lateral margins 

 depressed, and armed with three small spines, and the extremity with two. 



The ophthalmopoda are short and pyriform, scarcely reaching beyond the apex of the 

 first antennal tooth at the outer canthus of the orbit. 



The first pair of antennae (b) has the stylocerite reaching quite to the distal extremity 

 of the first joint ; the second and third joints are cylindrical and carry two unequal 

 flagella, the upper and outer being stout for about two-thirds the length of the rostrum, 

 from which point it suddenly becomes slender and extends a little beyond the extremity 

 of the rostrum. The inner and lower branch is slender from the base, and is about once 

 and a half as long as the rostrum. 



The second pair of antennas (c) carries a scaphocerite that is about half the length of 

 the rostrum, the outer margin is rigid and terminates in a sharp tooth that falls con- 

 siderably short of the distal extremity of the inner or submembranous portion, the 

 margin of which is fringed with hairs. 



The mandibles (d) are placed deeply within the oral cavity; the molar process is 

 cylindrical, and at the angle with the apophysis the psalistoma projects as a long, flat, 

 curved, rigid attachment, dentated only at the extremity ; at its base there arises a broad 

 triarticulate synaphipod fringed with hairs and not longer than the molar process. 



The first pair of siagnopoda is a small three-branched appendage ; the outer branch 

 is short and apically serrate, the median is broad, flat, and fringed on the inner, distal 

 margin with numerous spines of different thicknesses and a few ciliated hairs, the inner 

 branch is lunate, and distally and externally fringed with spines and hairs. 



The second pah' of siagnopoda (/) is formed on the inner side by two broad, short 

 plates, distally fringed with numerous spines, a small central branch, narrowing suddenly 

 towards the extremity, and a broad, flat, submembranous mastigobranchial plate that 

 projects anteriorly, considerably beyond the other branches, and expands posteriorly into 

 a broad, flat plate, rounded at the margins, and fringed with long ciliated hairs, all 

 radiating outwards and anteriorly. 



The third pair of siagnopoda (g) has a large squamous branch on the inner side, 

 a central three-jointed branch, narrow and subcylindrical, and at its base a broad, 

 squamous square-shaped plate, from the inner margin of which springs a long and slender 

 flagellum ; each branch is more or less fringed with ciliated hairs. 



The first pair of gnathopoda (h) is subpediform and short; the propodos is reflexed 



