COPEPODA 43 



middle of Ri II. lu the second pair of legs, on the anterior surface, pores are found near the lateral 

 margin of basip. II (on the left side a single group of lo pores and on the right side two groups of 6 pores), 

 in the basip. Ill medially to the insertion of Re I and in Re I near base of the process bearing Se; on 

 the posterior surface of basip. II, and at base of Se Re II and Se i — 2 Re III, a rather indistinct group of 

 pores is found. In the third and fourth pair of legs, groups of pores are also found posteriorly at base 

 of Se hasp. II and Re I ; in the fifth pair of legs only a single group was found in Re III posteriorly 

 (at base of Se I). 



As the number and arrangement of the maculae cribrosae in the mature male are scarcely dif- 

 ferent from those in the female, and as only the groups in the maxillulae, but not those in the nata- 

 tory legs, were observed in the Copepodites (stage IV— V) it seems to be possible, that the main- 

 purpose of the maculae cribrosae is connected with the sexual life (e. g. light organs). 



In front of the labrum and well distinguished from it, a fairly prominent elevation is found. 

 The labrum itself is rather elongated (PI. I, figs. 3 a — b and text-fig. 8 a). Anteriorly a transverse row 

 of delicate hairs is found, and posteriorly on each side of the median incision a transverse marginal row 

 of about 25 rather short lancet-shaped spines in addition to two somewhat convex rows, and a small group 

 of delicate hairs. The oral surface of the labrum has in front two well separated oblique groups. The 

 three following groups are placed more longitudinally as seen in fig. 3 b. Only corresponding to the 

 fourth central spot a few hairs are seen in a transverse row. The lamina labialis is, as seen in fig. 3 c, 

 fairly distinct without serrations ; in front of this an outer convex series consisting of fairly long hairs, 

 in continuation of the serrula 6-deutata, and three inner series of very delicate hairs are observed. 

 Behind the lamina labialis, between and upon the labial lobes and behind these a number of series and 

 rows of delicate hairs are found ; about their arrangement I refer to fig. 3 a. 



fc?. Size: 106 mm. (anterior division 8-5; urosome 2'i). The body is more slender and the process 

 of the posterior margin of the head is better developed. The abdomen consists of 5 somites, of which 

 the second is 2'5 as long as the first and 1-2 as long as the third. 



The antennulae (PI. I fig. 3 i) have the articular membranes between the 7—9 segments less 

 well developed than between the preceding and following ones. The number of the bristles shows a 

 similar difference from that of the female as in Calanus. The "^-Ustetasken" are powerfully developed and 

 the Sd of segment 9 is represented by a clavate structure (fig. 3!). The other appendages do not show 

 any difference from those of the females except the fifth pair of legs. In these the hasp, and Ri are 

 scarcely different, but the Re have no Si except the Re II of the pes V sin, which has the Si (?) 

 represented by a stumpy articulated process, prolonged into a somewhat twisted feathery spine, at the 

 base of which long and stiff hairs are seen; marginally a dense seam of hairs, as figured by Wolf en den 

 (fig. 9), is seen. 



Y. (V). Size: 8-2 mm. (anterior division 6-5, urosome 17). The shape of body is in main as in f$, 



but the lateral corner is more pointed and the urosome consists as seen in fig. 8 d of four somites, of 



which the first one is prominent ventrally. The mouth appendages seem in the main features alike 



those of mature females; the Re of the maxillulae possess as usually 10 for 11 setae. The second 



pair of legs differs by comparatively short Ri, which does not extend to the end of Re II, and by 



the wanting glandular pore at the base of Se I Re III; the same pore is wanting in the fourth pair 



6* 



