l6o COPEPODA 



Between the insertion of the antennae, (PI. VI figs 3 a— c.) an epistoma, directed forwards 

 and terminally covered with long, stiff bristles is found; between this and the well developed labrum, 

 which is gradually sloping anteriorly, a rather shallow portion is found; anteriorly the labnnii is 

 marked off by a chitinous transverse convex list, where the longitudinal muscles are fastened, which 

 move the marginal fringe of setae. The labrum bears in the middle two rather irregular rows of more 

 or less slender bristles. The marginal fringe consists in the middle on the well developed lobes of a 

 right and left group of fairly long hairs; more laterally a group of shorter hairs is found; orally an in- 

 distinct transverse row is found (cf. PI. VI fig. 3 a). The chitinous framework which supports the oral 

 surface of the labrum is in the main like, but less developed than, that of Euchirclla messhiensis (cf. 

 PI. IV fig. 2 a). In addition to the usual four central spots, 6 spots are present on each side. Just be- 

 hind the spots Nr. 4 a transverse group of short spines is found. The first lateral group of the longi- 

 tudinal series of delicate hairs is placed transversely, and fairly well separated from the more longitudinally 

 placed group 2; this again is well separated from the more or less fused groups 3 — 5, as seen in fig. 3 a. 



The lamina labialis (fig. 3 b) is divided into a median and, on each side, two lateral serrations, 

 which are connected with a chitinous skeleton. The area in front has, as shown in fig. 3 b, a rather 

 complicated structure; on each side, in the middle, a granular area converging in front, is found, and 

 more laterally several slightly convex longitudinal series of delicate hairs as well as a square spinous area 

 just in front of the serrula 6-dentata; the latter is, as seen in fig. 3 b, placed on a well developed chitinous 

 system. Behind and between the branches of the lamina labialis about 5 oblique rows of delicate hairs 

 are found on each side. M 6 b i u s has given a fairly good description of the oral surface of the labrum 

 and the lamina labialis. The labial lobes (fig. 3 c), which are well developed and rather prominent, pos- 

 sess about 5 somewhat irregular longitudinal series of comparatively short hairs, which, posteriorly, are 

 fused into fairly big median groups. The region behind the area labialis proper does not possess any 

 group of delicate hairs, but somewhat medially to the articular cavities of the maxillae is found a 

 group of 15—20 long, stiff setae, directed inwards and almost attaining the middle; in the middle, more 

 posteriorly, a group of 10 shorter setae, directed forwards, is found. 



f c^. Size: In one of the largest specimens (Thor St. 183) the total length was 6-34; anterior divi- 

 sion (2-53 + 1-95) 4-48; urosome i-86 mm. Sars' males measured 7 mm. and Giesbrecht's 5-45. 



The lateral corner of the fifth thoracic somite (text-figs 45 c — d) is distinctly more produced on 

 the left side than on the right; dorsally, a small marginal tooth is found, more developed on the left 

 side. The first abdominal somite has the genital pore on the left side, and is somewhat produced on 

 the right side; on the same side laterally and dorsally near the base of the somite a triangular tooth 

 is found. The segments 12—13 of the aiifeniiulac are well separated on the left side, but have on 

 the right side the articular membrane indistinct, posteriorly. The measurements are practically like 

 those in the adult females. The Ri of the ai/fcmiac has on the interior lobe 5 plumous setae, even 

 longer than in the female, in addition to two short ones. The mandibulac -possess, m co\\ixa.s,t to Sars' 

 and Giesbrecht's description, a well developed, but .soft-skinned, manducatory part with 4 short mar- 

 ginal teeth (PI. VI fig. 3e). The viaxillulae are better developed than described by Sars and Gies- 

 brecht, though they are probably without value for mastigation. The Le has 5 strong setae; the 

 Li I possesses at least three delicate bristles, the Li 2 a single short one and the Li 3 a single 



