COPEPODA 



4 1 



surface of the third basipodite of the first pair of legs. Scott has proposed to refer Calanus gracilis 

 Dana and Calanus robustior Giesbrecht to the same genus, in spite of smaller size, on account of 

 a similar hook. Possibly he is right; but as I have not had the opportunity of examining any spec- 

 imens of the two said species, I do not feel competent to judge in the case. 



3. Megacalanus princeps Wolfenden. 

 (PI. I figs. 3 a— i; textfigs. 8 a— d). 



1904. Megacalanus princeps n. sp. Wolfenden, pp. 112 — 113. 



1905. Macrocalanus longicornis n. sp. G. O. Sars, p. 7. 

 1905. Megacalanus bradyi n. nom. Wolfenden, pp. 1—3, pi. I, 



figs. 1 — 6. 

 1905. Nee. Megacalanus princeps Brady. Wolfenden, pp. 3 — 4, 



pi. I, figs. 7—9. 



b 



1906. Megacalanus longicornis G. O. Sars. Pearson, p. 6. 



1908. Megacalanus longicornis G. O. Sars. Farran, p. 21. 



1909. Megacalanus princeps Wolfenden. Scott, pp. 13 — 14, 



pi. I, figs. 12 — 18. 

 191 1. Megacalanus princeps Wolfenden. Wolfenden, pp. 196 



— 198, taf. XXII, figs. 1 -11. 



Text-figure 8. 



Megacalanus princeps Wolfenden. 



a. Head of adult female X 16. b. Abdomen of adult female X 16. c. Pes I in situ X 67. 



d. Abdomen of young female (stage V) X 16. 



Description f$. Size: 10-5 mm. (anterior division 8 - 5; urosome 2). The head is slightly produced 

 between the base of the antennulae and is without any crest. The rostral filaments are short and placed 

 on a low elevation just above the rostrum, composed of a short basal part and two slightly convergent 

 rather obtuse, fairly long spines, directed backwards and downwards. The five thoracic somites are well 

 distinguished; the fifth is laterally triangularly produced. Projecting from the hinder margin of the 

 head a small process, similar to that of Macrocalanus, though less prominent, is observed. 



The abdomen is only one fourth of the anterior division in length. The genital somite is as 

 long as deep and wide, and in front ventrally produced. 



The antennulae, which are at least 8 segments longer than the body, have all 25 segments 

 well separated, except the VIII and IX, with the articular membranes wanting posteriorly. The 

 segments increase in length from the 8 to the 17; beyond the 19 they are much shorter; the 23 is 1-4 

 as long as the 25, which is only n as long as the penultimate one. The 13 and 14 have in the distal 

 part, ventrally and exteriorly, a row of delicate teeth (according to Wolfenden they are found in seg- 

 ment 12 and 13). The bristles of the antennulae are rather delicate; the posterior setae of segment 

 23 — 24 are rather weak, and scarcely 1-5 as long as two distal segments (in Scott's figure they are 



The Ingolf-Expedition. III. 4. 6 



