153 



the spine makes an acute angle with the slightly compressed, straight, upper border of the 

 tergum, the spine being directed backward and little prominent; in younger individuals, however, 

 in which the carapace is i8 mm. long and less, the angle between the posterior margin of the 

 spine and the upper border of the terg-urn is much greater, al most right, so that in 

 these specimens the spine is more prominent, more turned upward and its upper margin does 

 not extend to the anterior border of the somite : in such specimens the spine looks as if arising 

 from the middle of the tergum. When the spine is worn off, like in the youngest specimen 

 from Stat. 12 or like in an adult, ova-bearing female from Stat. 256, it has the appearance 

 of a hump-like elevation, as described by Alcock. On each side of the base of the spine there 

 is a small, transverse groove, not far from and parallel with the anterior margin of the somite. 

 In old specimens the upper border of the tergum appears, posterior to the spine, sometimes 

 slightly fluted. The 4 rh and the 5 th tergum are rather compressed and in full-grown specimens 

 appear even bluntly carinate; on the 4 th tergum the upper border has a small notch or 

 angle at the posterior third and the carina of the 5 th reaches to near the posterior border of 

 the somite. Near its posterior margin the 5 th somite carries on each side of the upper border 

 a small, longitudinally grooved tubercle. In very young specimens the 6 ,h somite is tvvice or 

 even a little more than twice as long as the 5 th and as long or hardly shorter than the telson, 

 so, for instance, in the youngest specimen from Stat. 5 the 5" 1 somite is 2,5 mm. long, the 

 6 th 5,75 mm. and the telson 6,5 mm.; in older specimens the 6 th somite is comparatively 

 shorter, only a little more than one and a half as long as the 5 th , so, e. g., in 

 the adult female from Stat. 74 (Fig. 36a) the 5 th somite is 10 mm. long, the 6 th 16,5 mm., the 

 telson 23 mm., in an ova-bearing female from Stat. 256 these numbers are 8 mm., 13,5 mm. 

 and 20,5 mm. and in the adult male from the same Station 9 mm., 15 mm. and 20 mm. The 

 dorsal surface of the 6 th somite is deeply grooved longitudinally and this groove widens 

 slightly from before backward ; on each side of the groove the 6 th somite carries laterally a 

 longitudinal ridge, that reaches to the posterior third and that is situated about twice as far 

 from the lower than from the upper border. The telson of the adult male is one-third, that 

 of the adult female al most one and a half as long as the 6 th somite ; it is distinctly 

 grooved longitudinally and bears 4 pairs of dorso-lateral spinules, besides those at the tip. In 

 the adult the telson reaches as far backward as the outer uropods, sometimes it is a little 

 longer or shorter and in the full-grown female from Stat. 74 it is even a little shorter than 

 the inner uropod. 



The two pairs of antennae show nothing remarkable. The stylocerite reaches about to 

 the middle of 2 nd antennular article, which is a little shorter than the 3 rd , and the antennular 

 peduncle extends scarcely beyond the middle of the antennal scale ; the antennular flagella reach 

 by a little more than half their length beyond the rostrum. Antennal flagella slightly longer 

 than the body. 



External maxillipeds little shorter than the antennal scales, their exopodite extends almost 

 to the far end of their antepenultimate joint. 



The three posterior legs are short, like in other species of this genus, in the adult the 

 3 rd legs extend by half their dactyli or a little more beyond the antennal scales, while the two 



