REPORT ON THE CRUSTACEA MACRURA. 695 



The dorsal surface from the rostrum to the sixth somite is finely punctated with 

 shallow depressions. Those on the carapace are confluent, while on the pleon they form 

 small round hollows independent of each other. The surface of the carapace in the median 

 line projects anteriorly to a rostrum that equals the length of the first joint of the first 

 pair of antennas, or about twice the length of the ophthalmopod. On each side of the 

 median line is a deep groove that extends as far back as the orbital region, and gives 

 the appearance of a carina to the median line, which, however, is not elevated above 

 the rest of the carapace. The outer ridge of these grooves is longitudinally elevated 

 and anteriorly produced, and indicates the inner canthus of the orbit, which forms a 

 semicircle, the outer canthus being produced to a short point ; the margin then curves 

 round the base of the second pair of antennae and is produced at the fronto-lateral angle 

 to a sharp and rather prominent tooth, whence it recedes downwards obliquely to the 

 postero-lateral angle, which is the deepest portion of the lateral margin of the carapace. 



The pleon is anteriorly as deep as the carapace, equally compressed, it gradually 

 lessens in depth posteriorly in a ratio nearly similar to the lessening of the depth of the 

 carapace anteriorly, a circumstance that is due to the gradual and regular decrease of 

 the somites and coxal plates posteriorly. 



The telson (PL CXVIIL, z) is dorsally grooved, the groove widening to the posterior 

 lateral angles, the curved line of which is longitudinally armed with six small spines, 

 and there is also one on the outer angle of the posterior margin, which is fringed with 

 a row of hairs, in the centre of which is a small tooth representing the posterior 

 extremity of a small longitudinal ridge which occupies the median line of the posterior 

 portion of the groove. 



The ophthalmopoda (PI. CXIX. fig. 1) are short, scarcely reaching beyond the 

 projecting point of the inner canthus of the orbit ; the ophthalmus is small, orbicular, 

 and not larger than the peduncle. 



The first pair of antennae (PI. CXVIIL, b) has the first joint of the peduncle 

 subequal with the rostrum in length, excavate on the upper surface to receive the 

 ophthalmopod, and furnished on the outer side with a sharp pointed stylocerite, that 

 is shorter than the joint and fringed with hairs near the distal extremity. The second 

 joint is subequal in length with the first, subcylindrical, and furnished on the upper 

 and outer surface with a mat of shoft coarse hairs ; the third joint is half the length 

 of the preceding, longer on the inner than on the outer side, and terminally supports two 

 flagella, of which the inner is the longer and more slender and the outer short and robust. 



The second pair of antennae (c) is nearly as long as the animal and carries a scapho- 

 cerite that reaches as far as the extremity of the peduncle of the first pair ; it is broad, 

 foliaceous, and fringed at the extremity with ciliated hairs and strengthened on the outer 

 margin by a strong ridge that terminates in a tooth, which is little more than half 

 the distance from the base and lies embayed within the edge, from which point a 



