﻿52 



COPEPODA 



7. Eucalanus Attenuatus? Dana. 



(PI. I figs. 6 a — c; te.\t-iigs. 10 a— e). 



1S49. Calanus attenuatu.? n. sp. Dana. 



. Eucalanus attenuatus Dana. Dana. 



1892. — — — Giesbrecht, pp. 131. 



1894. — — — Th. Scott, pp. 28—29. 



1S95. — — — Giesbrecht, p. 24S. 



iSgS. — — — Giesbrecht & Schmeil, pp. 



20 — 21. 



1 90 1. — — — 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. 

 1 90S. 

 1909. 

 1911. 

 1910. 

 1912. 



"W'olfenden, p. 996. 



G. O. Sars, p. 2. 



Esterly, p. 133, figs. 7 a— c. 



Pearson, p. 7. 



Farran, p. 22. 



V. Bremen, p. 16, 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; urosome 0-58; total 

 length 5-18 mm. The head (text-figs. 10 a — b) is like that of Rhincalanus nasutus triangularly produced in 

 •> '■ lateral as well as in 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 urosome, which is scarcely one sixth as long as 

 the anterior portion, consists of three somites. The first (I <n) 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 labritm is in lateral view like that of Euc. clongatus 



Text-fig. 10. 



Eucalanus attenuatus Dana. YQ (stage V}. 



a. Head in lateral view >( i^- 



b. Head in dorsal view X if*. 

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



view X iS. 



c. 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 Fmc. 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 nrosoinc consists of four somites, of which the first one is 1-2 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. 



