550 HEV. T. R. R. STEBBING ON CRUSTACEANS [May 22, 



measured. The distinction of /. hargeri from /. pubescens is 

 only effected by attributing to Dana's description and figures a 

 minute accuracy to which they have no claim, and which at the 

 date of their production was scarcely ever accorded to small 

 crustaceans. Dana, for example, says " Caudal stylets half as 

 long as abdomen, three- or four-jointed," though his fig. 9 d shows 

 the stylets with single- jointed rami and only about one-fourth as 

 long as the pleon. That Pfeffer's Jcera antarctica may be an 

 additional synonym is of necessity conjectural. The solitary 

 specimen was imperfect and could not be dissected. The length 

 is given as 3-2 mm., and the greatest breadth as not much more 

 than one-fourth of the length ; just as Bovallius says of lais 

 hargeri, " the body is elongate, linear, four times longer than 

 broad." This, it is likely, refers to the male. In I. pubescens 

 the female loses something of her sleuderness of shape as the 

 marsupium becomes inflated. On the other hand, Pfeffer 

 definitely states that the finger is biunguiculate and that the 

 3-unguiculate finger, which he, like Sars, attributes to Jcera, was 

 not to be found on any of the limbs of the peraeon. He also 

 gives the colour as brownish, whereas the Falkland Island 

 specimens better agree with Bovallius's account of /. hargeri, as 

 " greenish white, almost hyaline." Pfeffer's description of the 

 damaged first antennae and of the uropods tallies well with what 

 is found in /. pubescens. 



Mr. G. M. Thomson found Tasmanian specimens of /. pubescens 

 in a tube with " Sphwroma quoyana M.-Edw.," but it may be 

 noticed that he also brought with him from Tasmania specimens 

 of Sphceroma gigas. Dr. Chilton found some of his New Zealaud 

 specimens free, but others " on a large Spharoma (probably 

 S. obtusa Dana) in Port Chalmers." The following description 

 refers to the specimens found at the Falkland Islands on Sphceroma 

 gigas (or lanceolatum). This association has been spoken of as 

 parasitic or semiparasitic. Apparently the small isopod makes use 

 of the large one as a kind of floating island, affixing its eggs to it, 

 and in adult life still clingiug on but doing no barm to its animated 

 lodging, which occasionally accommodates some minute zoophytes 

 on similar terms. 



Body narrowly elliptical, peraeon wider than head or pleon, but 

 almost parallel-sided except under the influence of the developing 

 ova, when also the sides of the segments become less widely 

 separated than before. The sides on the upper part are fringed 

 with small hairs. The pleon has a very small first segment, 

 followed by a rounded shield, fringed with minute hairs and 

 slightly projecting obtusely between the uropods. Head widest 

 at the eyes, obtusely projecting between the first antennae ; in 

 dorsal view the epistome obtusely prominent in advauce of the 

 rostral projection. 



Eyes very small, wide apart, about at middle of the lateral 

 margins of the head, each with only two crystalline cones set in 

 dark pigment (see figure in Beddard's lleport). First antennae 



