COPEPODA 



109 



Description, f^?. Size of specimen from Thor St 183 was 5-1 mm.; anterior division 4 mm.; 

 urosome 11 mm. Sars' specimens measured 4-85 mm., Farran's specimens 5-1, Scott's 5-4 and 

 Wolfenden's 37 — 4 mm. 



The frontal spine, which has a triangular base, has as seen in fig. 5 a the tip directed forwards 

 and upwards. The distance between the base of the frontal spine and the frontal organs, which are 

 placed on a small process, is almost straight with a low crest The rostrum is terminally bifurcate. 

 The shape of the body is scarcely different from Farran's figure; the anterior division is 2-^ as long 

 as wide and 3-6 as long as the urosome. The genital somite (fig. 5 b), which is distinctly 1-4 as wide 

 as long and i"i as deep as long, has a fairly prominent receptaculum semiuis. The relative length of 

 the abdominal somites and the furcal rami is the following: 42, 23, 19, 18 and 21; the furcal rami are 

 I'l as long as wide. 



The atitcnnae, which have the Re about 1-3 as long as the Ri, have the Ri I almost twice as 

 long as Re II, which is 17 as long as Re I, and a little shorter than Re VII. The Re I has a single 

 terminal seta on a conical protuberance, and the Re II 

 has 3 setae, of wliich the basal is the longest and 

 like the median one is placed on small protuberances. 

 The maxillulae possess 5 setae on Li II; the Li I has 

 no spinules posteriorly and the Li III has none ante- 

 riorly. The third basipodite of the inaxillipcds is 3 

 times as long as the endopodite and 1-3 as long as 

 the first and second basipodites combined ; the lamina 

 of the second basipodite (te.xt-fig. 26 b), which is folded 

 in a characteristic way, is in the whole length faste- 

 ned to the anterior surface of the segment; the inner 

 margin of the third basipodite is basally not straight 

 as shown in Farran's figure, but slightly convex as 

 figured by Scott 



The first pair of legs has a well developed 

 articulation between Re I and II, and the Se of Re II 

 almost reaches the end of Re II. The second pair of 

 legs has a well developed articulation between Re I and II, and a glandular pore at the base of Se 

 Re I; the terminal seta, which has 23 teeth, is a little longer than the Re III, and of equal length 

 to Re I— II. 



The second basipodite in the fourth pair of legs has about 25 knife-shaped spines as shown 

 in fig. 5 c. 



The oral surface of the labruni is fairly characteristic, as shown in fig. 5 d, especially the trans- 

 verse rows of granules around the median circular spot Nr. 4; the lamina labialis has a characteristic 

 granulation as seen in fig. 5 e, which also illustrates the area in front of it The arrangement of setae 

 in the lateral series behind the lamina labialis is not unlike that of G. pileatus: Ser. set i consists 

 of about 70 short setae placed in a longitudinal group: The series 2 seems to be represented by 3 



Text-fig. 27. Gaetatiiis latifrons G. O. Sars. 

 a. f9. Maxilla sin in post, view X 57- b. f9. Maxillipes 

 sin. in ant. view X 57- c. Y (stage IIIj. Maxilla dext. in 

 ant. view X 57- d. Y (stage III). Maxillipes sin. in an- 

 terior view X 57- e. Yd" (stage V,i. Pes V in anterior 

 view X 57- 



