COPEPODA 99 



lateral spines of the fifth thoracic tergite (text-fig. 25 b) are suddenly set off, slightly divergent and 

 reach the middle of the genital somite. The anterior division is 3-5 as long as the urosome, which 

 has the 4 somites and the furca of the following relative length viz. 46, 23, 19, 15 and 21; the furcal 

 rami are about rz as long as wide. The genital area is similar to that of Gaidius (text-fig. 25 b). 



The antcnnulae., which extend somewhat beyond the end of the abdomen, have the segments 

 24 — 25 almost completely fused and the appendages like those of Gaidius tcmiispimis and Gaetanus 

 armiger; the Sp. segm. 23 is at least twice as long as segments 24 — 25. The segments 2, 8 o^ 9 and 20 

 are of about equal length and about i-i shorter than segment 19. The antennae differ from those of 

 Gaetanus armiger (cf. Giesbrecht p. 221) by the Re II, which is distinctly twice as long as Re I, 

 and has not only the second but also the third Se placed on a conical protuberance. The mandibulae 

 differ from G. armiger by the fairly long plumous Si i of the third basipodite and the short Se 2 with 

 a few branches. The maxillulae and maxillae are scarcely different from those of G. armiger (text-fig. 

 25 i). The third basipodite of the maxillipes is 1-3 as long as the two first segments and 3 times as 

 long as the endopodite; the second basipodite has almost in the middle anteriorly on the exterior 

 surface a laminous process with a concavity turning forwards; its tip is somewhat produced and 

 rounded, and proximally to it a more or less distinct tooth is found (text-figs 25 k and j). The fourth L,i 

 of the hasp. II has in addition to the usual sensory lobe and two hairs a small conical process repre- 

 senting the third hair. 



The pes I has the articular line between Re I and II distinct anteriorly, except near the inner 

 margin; posteriorly only a faint line was observed; the pes II has the vSt, which has 25 well separated 

 teeth, distinctly longer than the Re III, in length almost equal to Re I— II. The hasp. II of the 

 fourth pair of legs (fig. 3 a) has about 25—30 stiff triangularly pointed marginal bristles, in the 

 main placed on the posterior surface. The number of secretory pores is completely like that of Gai- 

 dius^ with a pore at the base of vSe Re I in pes II. 



The oral surface of the labnim is in most respects like that of G. lati/ro?is (cf. fig. sd); the 

 bristles in group 3 — 5 are more like spines; the transverse rows of hairs between the circular spots 

 of group IV, as seen in fig. 3 b, are more like Gaidius tenuispinus. The lateral outline of the labrum is 

 very much like that of G. brevispinus, with three small elevations; no setae were observed on the anterior 

 surface in front of marginal row. The lamina labialis (fig. 3 c) is smooth and of another shape than 

 in G. latifrons, but in other respects, except for a somewhat different arrangement of the serrulae behind 

 the lamina, the labial appendages etc. are similar to those of G. latifrons. 



As most specimens are very pellucid the intestinal tract, especially the black hindmost portion 

 is generally quite distinct. It shows a characteristic structure with a large somewhat pointed coecal sac 

 directed towards the frontal spine, a small dorsal one opposite the wide oesophagus, and behind the 

 latter a gentle concavity, in which the oviducts with big eggs are placed (text-fig. 25 h). 



c?. Size of specimen from Thor St. 183 (?) was 5-04 mm.; anterior division 4 mm., urosome 

 1-04. Wolfenden's specimen measured 4-65 mm. 



The shape of the body is more slender; the anterior division is 3 times as long as wide 

 and almost 4 times as long as the urosome. The bifurcate rostrum is shorter and more clumsy 



13* 



