REPORT ON THE CRUSTACEA. MACRURA. 675 



The carapace is dorsally rouuded and smooth, excepting on the frontal crest and 

 rostrum, the former of which is armed with four teeth, and the latter on the upper 

 surface with other four, so far as known ; the lower surface is armed with two teeth, at 

 which point the rostrum is broken off. The frontal margin has the orbit but feebly 

 indicated, and the first antennal tooth tolerably developed, whence it gradually slopes to 

 the lateral margin. 



The pleon is smooth, and terminates in a telson that rapidly tapers to a point. 



The ophthalmopoda (fig. la) are pyriform, having the ophthalmus nearly half the 

 depth of the whole ; it is furnished with a large independent ocellus, and at the base of 

 the ophthalmopod there are a few slightly ciliated hairs. 



The first pair of antennae (fig. lb) has the peduncle shorter than the rostrum; the 

 first joint is excavate on the upper surface, fringed with ciliated hairs on the inner 

 margin, and furnished on the outer with a triangular stylocerite, the inner margin of 

 which is fringed with five long simple hairs. The second and third joints are cylindrical, 

 and tipped with fasciculi of long simple hairs, and terminate in two unecmal flagella, the 

 outer being robust, the inner slender and thread-like. 



The second pair of antennae (fig. lc) is about as long as the animal, and carries a 

 scaphocerite that is a little longer than the peduncle of the first pair of antennae, and is 

 probably subequal with the length of the rostrum. 



The mandibles (fig. lc?) are narrow, and have the psalistoma distinct from the molar 

 process, and support a moderately long two-jointed synaphipod. 



The first pair of siagnopoda (fig. lc) is three-branched; the outer branch is distally 

 square, supporting a stiff ciliated hair at each angle ; the middle branch is ovate and 

 furnished with a mat of hairs on the inner surface, and the inner branch is short and 

 fringed with hairs and stiff spines. 



The second pair of siagnopoda (fig. If) consists of three branches and a large 

 mastigobranchial plate ; the first branch is short, broad, and fringed with hairs ; the 

 second is bifid, each lobe being broad and ciliated ; the third branch is cylindrical, 

 tapering, and tipped with hairs. The mastigobranchia is broad, projects anteriorly as far 

 as it does posteriorly, and is fringed with a series of centrifugally directed hairs. 



The third pair of siagnopoda (fig. lg) is three-branched ; the first branch is bilobed, 

 the basal lobe being small and the distal large, ovate, and fringed with hairs ; the second 

 is cylindrical, biarticulate and flagelliform, and is sparsely fringed with hairs ; at the 

 base stands a bilobed mastisrobranchia. 



The first pair of gnathopoda (fig. 1/j) is short, broad, seven-jointed, and distally 

 reflexed ; it is furnished with a long, slender, flagelliform basecphysis, and the coxa carries 

 a short, triangular, mastigobranchial plate ; the several joints are fringed with hairs, those 

 on the inner distal margin increasing in character to fringed spines. 



The second pair of gnathopoda (fig. It) is four-jointed, long, slender, and fringed with 



