EEPORT ON THE CRUSTACEA MACRTJRA. 391 



rostrum that is elevated rather than projecting forwards. The carapace is about one- 

 third of the length of the animal, excluding the telson, and deepens laterally as it recedes 

 from the frontal margin. 



The five anterior somites of the pleon are subequal, but the sixth is about as long as 

 two of the preceding somites, about half as deep as long, and three or four times 

 longer than the telson. 



The ophthalmopoda are short, not reaching beyond one-half the length of the first 

 joint of the peduncle of the first pair of antenna?, and support an ophthalmus that is 

 considerably larger in diameter than the stalk. 



The first pair of antennae (PL LXVIIL, h $ ) has the peduncle nearly as long as the 

 carapace, having the first joint broad, flat, and straight on the inner, but arched and 

 furnished with a sharp tooth on the outer margin ; both margins are fringed with ciliated 

 hairs, the inner more sparsely. The second joint is nearly as long as the first, and the 

 third is nearly equal to the first and second together. The second and third are narrow, 

 cylindrical, and sparsely fringed with short ciliated hairs. The third joint carries at 

 its distal extremity two flagella ; the primary is long and slender, carrying at its base 

 a large bulbous swelling, formed by the coalescence of several annuli; it is larger in the 

 male than in the female, and in both sexes carries a series of closely-planted, membranous 

 cilia, disposed in transverse rows, more numerous in the male than in the female. The 

 rest of the flagellum is made up of numerous small, almost naked, articuh, there being only 

 one very minute hair attached to each articulus near the distal extremity. According to 

 Kroyer, the second pair of antennae reaches to about the same length as the animal, 

 but according to Mdne-Edwards' figure 1 it is twice the length of the animal ; in all the 

 specimens in the Challenger collection the flagellum is broken off at various lengths. The 

 outer or secondary branch in the female is short and rudimentary, having the articub 

 feebly represented, but in the male it is robust at the base, and at the third articulus 

 sends off a short branch that is stout at the base, but rapidly narrowing, and supporting 

 a long, curved spine, which seems capable of acting as a prehensile organ ; the main stalk 

 is still robust, and for some distance is apparently uniarticulate, and on the inner side of 

 its distal extremity is developed into a large tubercle, studded at the summit with minute 

 points ; the succeeding articuli are narrow and cylindrical, each successively becoming 

 smaller, so that the terminal portion, which measures about the same length as the 

 basal portion, gradually tapers to the extremity. 



The second pair of antenna? (PI. LXVIIL, c) has a strong j:>eduncle and a small and 

 slender flagellum, which, according to Kroyer, is once, and according to Milne-Edwards 

 more than twice, longer than the animal, and supports a scaphocerite that is not 

 of greater diameter than the last joint of the peduncle, but three times as long and 

 gradually tapering to a point. The inner margin is fringed with long, strong, delicately 



1 Ann. d. Sci. Nat., torn, xix., pi. x. 



