COPEPODA 



45 



Rhincalanus nasutus Giesbr. G. O. Sars, p. 2. 



— Th. Scott, p. 222. 

 Esterly, p. 137, fig. 10. 



— — Wolfenden, p. 996. 



— — Pearson, p. 8. 

 — — Farrau, p. 22. 



— — — v. Bremen, p. 18 fig. 14. 



— gigas Brady. Scott, pp. 24 — 25. 

 nasutus Giesbr. Farran pp. 18—19. 



1902. Rhiucalanus gigas Brad}-. Th. Scott, p. 450. 1905 



1902. — nasutus Giesbr. G. O. Sars, pp. 15 — 16 pis. 1905 



VI— VII. 1905 



1903. — — — J. C. Thompson, p. 16. 1905 

 1903. — — — Thompson & Scott, p. 242. 1906 

 1903. — — — Norman p. 135. 1908 



1903. — — Cleve, p. 368. 1908 



1904. — — Wolfenden, p. 128. I 9°9 



1904. — — — Cleve, p. 196. 1910. 



1905. — — — Farran, p. 30. 



Description f $. The females examined varied in size from 4-5 to 5 mm. When this characteristic 

 species is examined in lateral view, a marked difference is observed between the different specimens in the 

 outline of the head; in some animals a distinct pointed eminence is seen just in front of the insertion 

 of the antennulae, in others the outline in more even as figured by Sars; the size of this eminence 

 is probably dependent upon the preservation of the animal and the position of the antennulae in the 

 moment of death. The structure of the limbs is scarcely different from Giesbrecht's description. 

 In the exterior margin in the middle between Se I and II of the Re II <n> III in the first pair of legs 

 a small incision with a circular pore(?), through which a minute conical eminence projects, is seen 

 (glandular pore?). In the three last pair of legs I have not been able to find secretory pores with 

 certainty. 



As seen in Sars' figure the labriim, which is widely removed from the insertion of the anten- 

 nulae, is saddle-shaped and by a median line divided into an anterior and a posterior division (fig. 4a). 

 On the oral surface of the labrum, on each side almost attaining the middle, a row of fairly 

 long stiff hairs are found in addition to six short stout setae, more alike granules, in the middle partly 

 fused with transverse groups, and two posterior groups of partly sickleshaped spines, between which 

 large group of stout teeth are found (cf. PL I fig. 4e). The lamina labialis consists of a median and 

 two lateral divisions (fig. 4 c). In front of this we have laterally an inwards convex series of fairly 

 long bristles; the inner longitudinal row is posteriorly represented by row of rather short spines or 

 granules and anteriorly with irregular group of similar spines. Behind the lamina labialis and between 

 the serrula 6-dentata the setae are arranged as figured. The lobus labialis possesses 4 longitudinal 

 series or groups of hairs, which posteriorly and inwards are fused into a big irregular group of hairs, 

 extending between the two lobi. 



fo*. Size: 3-8 to 4*5 mm. The head is less produced in front of the rostral filaments. The ab- 

 domen, which is one fourth of the length of the anterior division consists of five somites; the first one 

 is dorsally and posteriorly produced into a distinct spine, corresponding to that found in the genital 

 somite of the female. The two first segments of the antennulae are well separated. The antennae 

 (cf. PL I fig. 4f) are more clumsy than those of the female, and so are the mandibulae, which have 

 a well developed manducatory lobe. The maxillulae, maxillae and maxillipeds, especially the 

 latter, which have the second basal segment scarcely twice instead of three times as long as wide, are 

 more clumsy than in the females, but scarcely less adapted for manducatory purposes. The mouth and 

 its surroundings are scarcely different from those of the female; the single specimen which I examined 

 had the spinulation of the labrum less coarse than in the female. The natatory legs are scarcely 

 different from those of the female. The internal sexual organs are found on the left side. 



