REPORT ON THE CRUSTACEA MACRURA. 803 



with a first antenna! tooth, situated near the outer canthus of the orbit, and a second 

 corresponding with the antero-lateral angle of the carapace, from which the anterior 

 margin directly recedes posteriorly in a horizontal line. 



The pleon has the dorsal surface smooth, with a small gibbous prominence near the 

 posterior margin of the third somite. 



The ophthalmopoda are short and orbicular, scarcely reaching beyond the antennal tooth. 



The first pair of antenna? has the peduncle tolerably robust ; the first joint is deeply 

 excavate to receive the eye, and carries a stiff sharp stylocerite, and the second and 

 third joints are short and cylindrical. From the extremity of the third joint, which 

 extends but little beyond the apex of the rostrum, arise two flagella, the outer and upper 

 of which is stout at the base, multiarticulatc, and from three to four times the length 

 of the animal ; the inner flagellum is slender, cylindrical, and equals the outer in length. 



The second pair of antennas has a short peduncle, and supports a scaphocerite that is 

 rounded at the extremity and strengthened at the outer margin by a longitudinal ridge 

 which terminates in a sharp tooth near the distal extremity. The flagellum is very long 

 and slender, being subequal with those of the first pair. 



The mandible is strong and has the psalistoma dentate and separate from the molar 

 process, and it carries a two-jointed synaphipod, of which the distal joint is ovate and 

 fringed with hairs. 



The siagnopoda exhibit nothing of specific value. 



The first pair of gnathopoda is six-jointed ; the terminal joint is long-ovate ; the 

 basis carries a long slender ecphysis, and the coxa supports a membranous mastigobranchial 

 plate, to which is attached a short podobranchial plume. 



The second pair of gnathopoda is long and pediform, and terminates in an ovate 

 spatuliform joint ; the basis carries a slender ecphysis, and the coxa the rudiment of a 

 mastigobranchial plate without any modification of a podobranchial plume. 



The first pair of pereiopoda is chelate, the chela being small ; the propodos is slender 

 and short ; the dactylos is minute ; the carpos is long, slender, cylindrical, and smooth ; 

 the meros and ischium are long, slender, and united by a peculiar, long, overlapping joint, 

 and armed on the lower margin with a series of long spine-like teeth. The second pair, 

 which is about twice the length of the first, is chelate, the chela having the dactylos 

 cylindrical and the pollex concave ; the propodos is long and subcylindrical, but short 

 compared with the carpos, which is about four times as long and half the diameter ; the 

 meros and ischium are together about equal in length to the carpos, and are united by 

 a long overlapping joint and armed on the lower margin with a few teeth. The three 

 following pairs of pereiopoda are about as long again as the second ; the third and fourth 

 terminate in a comparatively long and waved dactylos, whde that of the fifth pair is 

 short and rudimentary. The propodos is short, broader at the distal than at the carpal 

 extremity, and carries a brush of hairs at the distal extremity, amongst which in the 



