190 



COPEPODA 



anteriorly convex line divided into an anterior and a posterior smaller part; the labrum proper is beset 

 with a number of shorter and longer bristles, the somewhat complicated arrangement of which is most 

 easily understood by studying fig. 8 c. 



The oral surface of the labrum (PI. VII fig. 8 d) shows a rather characteristic structure; the 

 longitudinal series on each side consists anteriorly of an oblique group of fairly long and strong spines; 

 behind this two or three groups of comparatively long and slender setae are found, followed by a more 

 medially placed, almost square, area of short spines; behind the last mentioned group, which is only 

 separated from the corresponding one of the other side by a narrow smooth area, an oblique one covered 

 with delicate hairs is found. The lamina labialis seems to be represented by a very short transverse 



plate; in front of it and the serrula 6-dentata a medial short row of fairly long 

 setae and a longer curved lateral one of shorter setae are found. Behind the 

 lamina labialis and between the serrulae is found on each side a short group 

 of strong spines, almost fused with the corresponding one of the other side, as 

 well as a more posterior and lateral group. The arrangement of the delicate 

 hairs behind, as well as upon, the labial lobes consists, as in X ovatus (fig. 14 b) 

 of a median and, on each side, a lateral group, in addition to more laterally 

 placed scattered setae. 



fo*. Size of specimen from Thor St. 214 was 474 mm.; anterior divi- 

 sion 3-14 mm.; urosome i-6 mm. Sars' specimens measured 4-5 mm. 



The fifth thoracic somite is well marked out, and its lateral corner is 

 rounded. The comparative length of the abdominal somites and the furcal 

 rami is 15, 83, 47, 52, 10 and 20. 



The antennulae extend somewhat beyond the end of the thorax, and 

 are distinctly attenuated towards the end; they are proximally to segment 14 

 slightly curved, and the proximal portion forms an obtuse angle with the 

 more attenuated distal portion. The segments 8 <v 9 are completely fused with 

 segments 10 — 12; the segment 13 is well separated, and the segments 21 — 21 

 generally so. "iBsthetasken" are beyond segments 8 <n> 9 only observed in seg- 

 ments 12, 14, 15, 16 and 25. The antennae have comparatively long setae, 

 and the second outer segment is distinctly restricted in the middle. The manducatory part of the 

 mandibulae is more soft-skinned than in the female, and has less powerful teeth ; the third basipodite 

 is much wider than in the female, almost as wide as long, and has the inner setae short and delicate. 

 The maxillulae are more elongated, and their setae are less powerful than in the female ; the Li II has 

 only a single seta, the Basp. Ill has only 4, and the Ri I has 2 for 3. The maxillae are in general 

 shape like those of the females, but their appendages are less developed. The maxillipeds are as figured 

 by Sars, but are more slender and delicate. 



The natatory legs are scarcely different from those of the female. 



The fifth pair of legs is scarcely different from Sars' figure; the terminal attenuated part of 

 the right endopodite is articulated, and corresponds to the third segment. 



Text-fig. 58. 

 Scaphocalanus mag?ms T. Scott, 

 a— i. Left lateral corner in 8 

 different adult females X 59- 

 j— k. Same of two young males 



(St. V) X 59- 







