150 "TERRA NOVA" EXPEDITION. 



Rhnarks. — The specimens described above as belonging to C. levis, G. M. 

 Thomson, diminish, although they do not altogether obliterate, the difference formerly 

 stated to exist between that species and this as regards the dorsal outline of the 

 carapace. The specimens now recorded tend to depreciate another of the characters 

 separating the two species, inasmuch as the oblique ridge of the carapace becomes so 

 merged in the general rugosity of the surface as to be, in certain specimens, altogether 

 indistinguishable. Nevertheless, the specimens are at once easily separable from those 

 referred to C. levis, even when occurring in the same gathering, by the strong pitting 

 of the surface of the carapace. The pits are so large and so close together that 

 the intervening surface forms an irregular raised network and the carapace may 

 be described either as pitted or as reticulately rugose. This sculpturing is, of course, 

 to be distinsuished from the minute reticulate texture which the whole of the 

 exoskeleton shows, as it does in many other Cumacea. 



The remaining differences formerly enumerated between this species and C. levis 

 concern chiefly the proportions of the distal segments of the first leg and of the 

 peduncle of the uropod. In both cases careful measurements of specimens in the 

 present collection show differences of the same kind, though somewhat less than those 

 stated in my former description ; the dactylus of the first leg is three-fourths as long 

 as the propodus as against a proportion of four-fifths or a little more in C. levis, and 

 the peduncle of the uropod is longer than the last somite by nearly one-fourth in the 

 female and one-third in the male. In C. levis the peduncle is only about one-sixth 

 lono-er than the last somite. 



The double lateral ridge of the last thoracic somite, mentioned only for the male 

 sex in the original description, is present also in the female. 



18. Cyclaspis coelehs, n. sp. Fig. 5. 



Occurrence. — Stations 133, 135, and 136. Spirits Bay, near North Cape, New 

 Zealand. Plankton, at 20 metres, 3 metres, and surface. Five males (inch holotype). 



Description. — Adult male. Total length 5 • 6 mm. 



Eesembling in general form the male of C. thomsoni but with the carapace shorter 

 and deeper, its height being about two-thirds instead of little over half its length. 

 Surface of carapace obscurely and irregularly rugose or pitted. On either side, just 

 below the lateral liml)s of the frontal suture, is a broadly rounded prominence, 

 somewhat elongated antero-posteriorly, very conspicuous when seen from above,- 

 occupying the position of the anterior upper tubercle of C. elegans. Behind the middle 

 of the carapace is a faintly marked oblique ridge inclined backwards and downwards 

 and dying out below in the general rugosity of the surface. A curved ridge running 

 backwards from the antennal tooth is very prominent. The ocular lenses are 

 conspicuous ; three very large ones form a triangle dorsally and a pair are . set close 

 together at the tip of the ocular lobe, while three others on each side, overlapped by 

 the upper margin of the lateral plate, are only indistinctly seen. 



