COPEPODA 



217 



a curved row of fairly long setae, in the middle connected with the opposite side, is found; somewhat more 

 posteriorly, and extending from the middle anteriorly to the hinder margin posteriorly, an elongated 

 semicircular row is found (in fig. 14 a, this row is wrongly represented as being separated from that of 

 the opposite side); this row is several setae high, and the length of its setae decreases backwards. 

 More posteriorly another convex row of shorter setae is found, and between the end of this row and 

 the mentioned outer row a short oblique series is found. Posteriorly and laterally scattered hairs are 

 found, and more medially an almost transverse row. The posterior marginal setae are well developed. 

 The oral surface of the labrum (PI. VI fig. 14 b) shows greatest similarity to that of X obtusifrons (PI. 

 VII fig. 9 c). Laterally, in front, a big area with short setae is ob- 

 served, belonging to the marginal system. The first lateral group 

 consists of a few granules, and is well separated from the three fol- 

 lowing more or less fused groups of fairly strong setae ; posteriorly 

 one or two groups of more delicate setae. The arrangement of the 

 transverse rows is seen in figure. The lamina labialis (fig. 14 c) 

 seems to be represented by two rounded structures meeting in the 

 middle; in front of it the two usual rows of setae are found. The 

 arrangement of the hairs behind and between the serrula 6-dentata 

 is seen in figure. In the middle between the labial lobes a large 

 group of densely placed hairs is found, which laterally is continued 

 into an inner marginal row of longer and a more lateral row of 

 shorter hairs. Independent of these, and more laterally, two rows 

 of short setae are found. 



f o*. Size of male from Thor St. 82 was 5-24 mm.; anterior 

 division 3-93 mm.; urosome 1-31 mm. Th. Scott's specimens measured 

 c. 4 mm., Giesbrecht's 4-5, Esterly's 5-3 and A.Scott's 44 mm. 



The shape of the body is somewhat more slender than in 

 the female. The rostrum is more slender than that of the female, 

 and its branches have sometimes a delicate terminal filament. The 

 fifth thoracic tergite is fairly well marked in front, and is distinctly 

 rounded (text-fig. 69 a). 



The abdomen, which is about one third of the anterior di- 

 vision, has on the left side of the first somite a backwards directed, rather prominent process, in which 

 the genital opening is found; a fairly distinct serrated seam was found along the hinder margin of the 

 second to the fourth somites. 



The antennulae extend to the end of the fourth abdominal somite, and are almost straight. 

 Segments 8^9 to 13 are more or less fused, but the articular membranes between segments 80^9 and 

 10, and between 12 and 13, are fairly well developed anteriorly; the segments 21 and 22 are fused on 

 the right side, while segments 24 and 25 are well separated on both sides. The articulation between 

 segments 14 and 15 is only poorly developed. Most of the bristles are soft-skinned, and very much 

 like sensory setae. One or two "^sthetasken" were found in all segments from 1—19; a proximal seta 



The Ingolf-Expedition. III. 4. ^° 



Text- fig. 69. Scottocalanus Thorii n. sp. f d"- 

 a. Abdomen X 15- b. Pes V dext. from 

 the left and partly from below X 59- 

 c. Re III dext. from below, d. Pes V 

 sin. Re III from the right side. 



