REPORT ON THE CRUSTACEA MACRURA. 701 



furnished with an antennal tooth that corresponds with the external canthus of the 

 orbit, and with another situated above the fronto -lateral angle. 



The pleon is dorsally smooth and has the sixth somite but little longer than the 

 preceding, and terminates in a telson that is about a third shorter than the lateral 

 plates of the rhipidura. 



The ophthalmopoda are short, the ophthalmus being orbicular and ,sc;ircely of 

 greater diameter than the stalk. 



The first pair of antennae (b) has the first joint of the peduncle excavate on the 

 upper surface, and is distally fringed with a double row of short stiff spinules, regular 

 in their length and comb-like in appearance, while on the outer side a sharp-pointed 

 stylocerite projects quite equal to the length of the joint. The second and third 

 joints are cylindrical, furnished with a mat of hairs on the lower surface, and terminate 

 in two long, slender, multiarticulate flagella, the outer and upper of which is stouter 

 near the base and divides into two rami at a short distance from its base, the inner 

 of which is truncate ; whereas the inner and lower flagellum is about two-thirds the 

 length of the outer, and gradually tapers from the base to the apical extremity. 



The second pair of antennae (c) carries a slender flagellum that is as long as the 

 animal, and a broad ovate scaphocerite, armed on the outer margin, half-way between 

 the base and the apex, with a sharp tooth, from which a line of division, like the 

 diaeresis of the outer plates of the rhipidura, crosses the plate transversely in a curved 

 line ; a long, tapering, and slightly curved phymacerite springs from the inner surface 

 of the coxal joint. 



The mandibles (d) are without a synaphipod, but possess a molar process and 

 distinct psalistoma, the latter being dentated with three sharp denticles, and the 

 former obliquely truncate and furnished with minute spinules and denticles. 



The first pair of siagnopoda (e) is small, feeble, foliaceous, and three-branched ; the 

 outer branch is short, ovate, and tipped with a couple of long hairs ; the middle branch 

 is broader at the distal extremity than at the base, and is fringed at the distal inner 

 margin with short spinules, and the inner branch is short and circular. 



The second pair of siagnopoda (_/") carries a long foliaceous process, produced to a 

 point and reaching posteriorly far into the branchial chamber ; it is furnished with long 

 hairs that sweep the surface of the branchial plumes to then- furthest extremity. 



The third pair of siagnopoda (g) is formed as in Atya sulcatipes, but has the digital 

 process somewhat more slender. 



The first pair of gnathopoda (h) resembles that of Atya sulcatipes, and like it the rudi- 

 mentary mastigobranchial plate does not support a branchial plume, but is fringed with a 

 series of flat pointed spinules, and the basecphysis is proportionally more slender. 



The second pair of gnathopoda (i) is pediform, and differs from that in Atya sul- 

 catipes in being more slender and having the terminal joint longer in proportion. 



