226 "TERRA NOVA" EXPEDITION. 



only 9 mm. There is thus a considerable difference in size between adults of both sexes. 

 There are other interesting sexual differences in this species. In the adult male the 

 base of the propodus of the second thoracic limb bears a rather long and stout blunt 

 process, which makes this appendage in the male a prehensile limb. The process is quite 

 absent in the female and only slightly developed in the immature male specimen. This 

 character is interesting, as no other genus of Eubranchiate Sphaeromids exhibits such 

 a sexual difference. 



Further, on the third to the eighth pairs of thoracic limbs of the male the carpus 

 and merus bear on their inner margins a dense pad of short stout setae just like a brush. 

 These are not present in the female and only slightly developed in the immature male. 



The stylet on the second pleopod of the male is about half as long again as the 

 inner ramus. 



C. SPHAEROMINAE PLATYBRANCHIATAE. 



Genus CASSIDINA, Milne-Edw., 1840. 



33. Gassidina typa, M.-Edw. 



G. typa, M.-Edw., 1840, p. 224, pi. XXXII, figs. 10-16; Hansen, 1905 (1), p. 129. 

 C. neo-zealanica, G. M. Thomson, 1888, p. 264, pi. XIV, figs. 1-4; Stebbing, 1900, p. 562 ; 

 Hutton, 1904, p. 263 ; Thomson, 1913, p. 247. 



Occurrence. — Station 134, Spirits Bay, near North Cape, New Zealand, 11-20 

 fathoms, bottom fauna, one female. 



Remarks. — The single specimen measm-es 6 mm. in length and about 4 mm. in 

 lireadth. Hansen has identified C. neo-zealanica, Thomson, with Milne-Edwards' species, 

 and with this opinion I am in agreement. My specimen agrees more closely with 

 Milne-Edwards' figures than with Thomson's. For instance, the latter author figures 

 the abdomen as consisting of two somites only, whereas in my specimen four 

 somites are indicated, the suture marking off the first somite not visible in the centre 

 and not reaching the lateral margins, while that marking off the second segment is not 

 complete in the median dorsal line but does extend to the lateral margins. This 

 condition agrees absolutely with Milne-Edwards' figure. The liody generally is clothed 

 dorsally with short hairs, which are more numerous laterally than in the centre of the 

 1)ody. Between the bases of the hairs the surface of the body is microscopically honey- 

 combed. The proportions of the first and second antennae and the form of the epistome 

 agree very well with Milne-Edwards' figures, and differ somewhat from those of 

 Thomson. The first antenna is slightly longer than the head, and quite reaches the 

 end of the peduncle of the second antenna. The flagellum has eight joints. The second 

 antenna reaches a little beyond the posterior border of the first free thoracic somite, 

 and its peduncle is as long as the head. The flagellum has twelve joints. These differences 

 are small, and considering the many points of close resemblance between Milne- 

 Edwards' and Thomson's accounts, and the fact that both species are found in New 



