52 



COPEPODA 



7. Eucalanus Attenuatus? Dana. 

 (PI. I figs. 6 a — c; text-figs. 10 a— e). 



1849. Calanus attenuatus n. sp. Dana. 



. Eucalanus attenuatus Dana. Dana. 



1S92. — — — Giesbrecht, pp. 131. 



1894. — — — Th. Scott, pp. 28— 29. 



1S95. — — — Giesbrecht, p. 24S. 



1898. — — ' — Giesbrecht & Schmeil, pp. 



20 — 21. 



1 901. — — — Cleve, p. 6. 



1903. — — — Norman, p. 135. 



1903. — — — Cleve, p. 362. 



1900. — — — Wheeler, p. 167. 



1903. — — — J. C. Thompson & A. Scott, 



pp. 242. 



1903. Eucalanus attenuatus Dana. J. C. Thompson, p. 15. 



1905- 

 1905. 

 1905. 

 1906. 

 1 90S. 

 1908. 

 1909. 

 1911. 

 1910. 

 1912. 



Wolfenden, p. 996. 



G. O. Sars, p. 2. 



Esterly, p. 133, figs. 7 a— c. 



Pearson, p. 7. 



Farran, p. 22. 



V. Bremen, p. i5, fig. 12. 



O. Pesta, p. 21. 



O. Pesta, p. 20. 



Steuer, p. 21. 



Sewell, p. 357. 



Description y$. (Stage V). Length: anterior division 3-34 — 1-26 = 4'6; nrosome 058; total 



length 5-18 mm. Tlie head i text-figs. 10 a — b) is like that of Rhincalanus ?iasutus triangularly produced in 



•' '' " lateral as well as iu dorsal view. The fifth thoracic somite (text-fig. 



IOC — d) is fairly well marked out, especially dorsally, and its lateral 

 corners are slightly produced and rounded. The rostral filaments 

 (text-fig. 10 e) are long and slender, and placed on a long bifurcate 

 basal portion. The urosomi\ which is scarcely one sixth as long as 

 the anterior portion, consists of three somites. The first (I <^ II), which 

 does not show any trace of receptacula seminis, is longer than the 

 two following combined; the fourth somite is completely fused with 

 the furca, which has the longer branch on the left side. The St. 2 

 sin. is distinctly longer and more powerful than the other setae. 



The structure of the mouth appendages and natatory legs 

 scarcely shows differences of any importance from Giesbrecht's 

 description; the Ri 2 of the maxillipeds has only 3 instead of 4 Si. 

 No glandular pores were observed in the four pair of legs. 



The labriim is in lateral view like that of Euc. clongatus 



Text-fig. 10. 



Eucalanus attenuatus Daua. YQ (stage V}. 



a. Head in lateral \-iew X iS- 



b. Head in dorsal view X iS. 

 c— d. Abdomen in lateral and dorsal though less produced. The Oral surface differs from that of the other 



view X 1 8. 

 e. Rostral filaments X 27. species i) by anterior group of minute spines laterally near free 



margin, and 2) by the different number and arrangement of three first groups of spines in longitudinal 



series, as seen by comparing figures 5 a and 6 a; the structure of the three posterior groups and of the 



transverse rows are scarcely different from that of Euc. clongatus. About the small differences existing 



in the structure of the labium etc. I refer to fig. 6 b. 



Yc? (Stage V). Length : 5 mm. The lateral corner of the fifth thoracic somite is less produced. 



The urosovic consists of four somites, of which the first one is i-2 as long as the second, which is 



again 1-3 as long as the third and fourth. In this species the fifth pair of legs (fig. 6 c) shows, as a 



whole, more similarity to that of the adult male of E. attenuatus than in E. clongatus. The right leg 



is the shorter, and the segments are more attenuated than in the mature male. 



