148 "TERRA NOVA" EXPEDITION. 



basis itself, although its relation to the longer distal segments is much the same as in 

 C. elegans. In the first legs the distal segments are together distinctly longer than 

 the basis. 



A male specimen has a total length of 5 " 6 mm. The general form agrees closely 

 with that of the male C. elegans, but the disposition of the ridges of the carapace 

 resembles that of the female described above. The lateral enclosed area is relatively 

 smaller than in the female. The carapace differs from that of the male C. elegans in 

 having no tubercle at the posterior lower corner of the enclosed area (although this 

 tubercle may be inconspicuous in C. elegans, as in the specimen described above) and no 

 ridge running thence to the hind margin, while the posterior vertical ridge forks at its 

 upper end, the anterior limb of the fork forming part of the upper enclosing ridge. 

 The surface between the ridges is somewhat coarsely but sparsely granulated. 



15. Cydaspis argiis, Zimmer. 



a argus, Zimmer, 1902, p. 444, figs. A-C ; id. 1913, p. 470, pi. xlvi, fig. 70. 



a histriata, Zimmer, 1902, p. 447, figs. D-F ; id. 1913, p. 470; Stebbing, 1913, p. 39. 



C. hiplicata, Caiman, 1907b, p. 17, pi. iii, figs. 4-15; Zimmer, 1913, p. 470. 



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

 Zealand. Plankton, at 20 metres, 3 metres, and surface. Many specimens. 



Remarks. — The majority of the adult females in this collection differ from the 

 syn types of C. biplicata in their greater size (total length 5"1 mm., as against from 

 3 • 6 to 4 • 2 mm. ) and less strongly calcified integument ; in having the dorsal edge 

 of the carapace more strongly arched, the lateral ridges much less marked, not con- 

 verging above, and situated a little further forward on the carapace ; and in having 

 the abdominal somites relatively more robust. In all these characters they resemble 

 the immature female described by Zimmer as C. bistriata. They further difi"er from 

 the syntypes of C. biplicata in having the posterior tooth of the crest of the caparace 

 less abruptly defined, and all the abdominal somites with a strong dorsal keel ; this 

 keel is elevated towards the hinder end of each somite, forming a blunt tooth, so that 

 the dorsal outline of the abdomen appears serrated. The fifth abdominal somite is 

 hardly more than twice as long as deep, while in C. biplicata the proportion is about 

 two and a half to one. 



These characters leave little doubt that the specimens belong to the same species 

 as the holotype of Zimmer's C. bistriata, and they might have been urged as evidence 

 for the distinctness of that species if it had not been for the presence of some distinctly 

 smaller females from Station 136. One of these, an ovigerous female, measures only 

 4" 6 mm. in total length, and while it agrees with the others in the outline of the 

 carapace and in the character and approximate position of the lateral ridges, it has 

 the dorsal keel of the abdomen much less conspicuous and the somites much more 

 slender, the fifth, for instance, being 2 • 3 times as long as deep. In general appear- 

 ance, as in size, this specimen is, to a great extent, intermediate between the syntypes 



