41 



the male, but those of the 2"'' somite become gradually shorter, more dentiform. The spiniform 

 teeth on the thoracic sternum are less sharp, more obtuse in these older specimens; in the male 

 the acute teeth, with which the abdominal sterna are armed, remain spiniform and conspicuous, 

 but in the older females they finally disappear, except on the i"' sternum. 



The largest male, one from Stat. 297, is 145 mm. long; the abdomen, measuring 92 mm., 

 is three-fourths longer than the carapace. The i*' pair of antennae, 86 mm. long, are almost 

 as long as the abdomen and two-thirds longer than the carapace (53 mm.); the peduncle, the 

 I*' joint of which, 28 mm. long, appears almost Ys longer than the two following joints taken 

 together, extends by the terminal joint and half the penultimate beyond the antennal peduncle. 

 The longer inner flagellum (36 mm.) is about one-fourth longer than the i^' joint of the 

 peduncle and the peduncle (50 mm.) is hardly shorter than the carapace. 



The largest female, a female with eggs from Stat. 38, measures 175 mm., the abdomen 

 (115 mm.) is almost twice as long as the carapace. The i^' pair of antennae, 71 mm. long, 

 are much shorter than the abdomen, measuring not yet two-thirds its length and they are 

 little longer than the carapace, only one-fifth. The peduncle, the i^' joint of which, 29 mm. 

 long, appears '/., longer than the two following taken together, extends only by its terminal 

 joint beyond the peduncle of the outer antennae. The flagella are much shorter than in 

 the male, the longer flagellum, indeed, is not longer than the i"' joint of the peduncle, but 

 one- fourth shorter, the peduncle, finally, measures five-si.xths the length of the 

 carapace. We may infer from the preceding observations that in adult specimens the anten- 

 nular flagella are longer in the male than in the female. In younger male specimens, 

 however, they are comparatively shorter. Alcock's description of the inner antennae is therefore 

 only apposite to the young male and to the female: the antennular peduncle being but little 

 shorter than the carapace, his words "the antennular peduncle is more than half the length of 

 the carapace" are not clear. 



The outer antennae of the largest male from Stat. 38, which measures 134 mm., are 

 490 mm. long, i. e. more than 3Yj-times the length of the body, according to Alcock they 

 should be more than twice as long as it ; the peduncle, measured on the lower side, appears 

 to be 35 mm. long, nearly one-fourth the length of the body. The antennal peduncle is as 

 plentifully spinose as in the first described young female. The outer margin of the penultimate 

 joint is armed with 5, that of the terminal joint with 3 spines, that distally increase in length; 

 there is a strong spine at the far end of the inner margin of the ])cnultimate joint and 3 or 4 

 smaller ones on that of the last and these s])ines also gradually increase in size distally. Two 

 rows ot small s]jinules occur on the upper surface of the penultimate joint, one parallel with 

 the outer, the other parallel with the inner margin and a few small spinules exist on the upper 

 surface of the last joint. The lower surface of the antennal peduncle is likewise beset with 

 small spinules, that are ])artly arranged in longitudinal rows. The outer antennae of the female 

 agree with those of the male, as regards their length, armature and other characters. 



Concerning the maxillipeds I will onI\- remark that the exopod and flagellum of the 

 3'^' or external pair have the same form and length as those of the 2'"'; the exopod of the 

 1"^ maxillipeds (PI. II, fig. 5(;) is somewhat longer, more <Milarged, narrowing distally and hairy 



S1B0GA-E.\PEUIT1E XXXIX fl^. 6 



