COPEPODA n 



Giesbrecht refers this species to Monoculus finmarchicus Gunner us, (p. 32 — 33). Kroyer 

 (1848 p. 528) has already shown that Gunner us species was a Calanus, but he thinks that the 

 decsription is too incomplete for a sure indentifi cation. In contrast to Giesbrecht I think that it 

 is quite impossible to tell if the species belongs to Cal. finmarchicus or to young specimens of Calanus 

 hyperboreus. The one figure in natural size shows a small animal (c. 2 mm. long) even less robust 

 than most specimens of C. finmarchicus; this figure and the author's remarks about »quite small 

 animals« certainly speaks against its identification with Cal. hyperboreus, but the remark about, the 

 very pellucid, shining colour without indication of the reddish tint which is most often found in Cal. 

 finmarchicus, especially the antennulae, does not bear out the same opinion. The biological conditions 

 under which the two species are found in the polar region, are almost identical, and do not allow 

 any conclusion. But as the name Cal. finmarchiats has been once recognized, and as it cannot with 

 better, probably with smaller, right be applied to Cal. hyperboreus, I think it right to follow Giesbrecht. 

 In other respects as far as the synonymy is concerned I refer to Giesbrecht; as I have however 



As I have had the opportunity of examining Kroyers original specimens of Cal. carinatus and cristatus, I think that 

 a few words of their systematic position would not be superfluous, even if these species belong to another geographical region. 



Calanus carinatus Kroyer. 

 1849. Calanus carinatus n. sp. Kroyer, p. 554. 

 1856. — brevicornis u. sp. Lubbock p. 11. 

 i860. — — Tbk. Iyubbock, p. 117. 



1892. — — Lbk. Giesbrecht, p. 90; taf. 6, 7, 8. 



Of this species Kroyer has examined a single not very well preserved adult female from the coast of Brazil. In 

 spite of the differences enumerated below I think it is identical with the midatlantic species, which Giesbrecht has referred 

 to C. brevicornis Lubk. The total lenght was 2'o-(- o-6 = 2'6 mm. The marginal frontal keel is more prominent than figured 

 by Giesbrecht (t. 6, fig. 7) and the rostral spines are more stiff, but the lateral outline of the labrum shows the same 

 characteristic structure as figured by Giesbrecht. The fourth abdominal somite is dorsally 1-2 as long as the fifth one as 

 shown in Giesbrecht's fig. 18, but in contrast to his text, in which he writes that the fifth somite is a little longer than 

 the fourth. 



The antennulae extend a little beyond the tip of the fourth abdominal somite; the segment VIII— IX are less 

 well separated than the rest. The distal setae of segm. VIII and XII are not spinelike. The measurements are at least 

 different from Giesbrecht's figure of the male (taf. 8 fig. 5); the segment 24 is a little shorter than the 23, which is 

 scarcely as long as the 22. The 25 segment is rather mutilated, but seems scarcely to be half as long as the preceding one. 



No marginal setae were found along the inner margin of the second basipodite of the pes II, IV and V, and no teeth. 

 The first Se of the Re III divides the outer margin in equal parts in the second pair of legs but in the fourth pair the 

 portion, proximal to Se I is 17 (not 1-4 as in brevicornis) as long as that distal to it. 



Calanus cristatus Kroyer. 



1845. Calanus cristatus 11. sp. Kroyer, pi. 41, figs. 6 a— k. 



1849. — cristatus Kr. Kroyer, pp. 546 — 550, p. 553. 



1884. — — Kr. Poppe, pp. 282—286; taf. XX, fig. 1—6. 



1892. — — Kr. Giesbrecht, p. 91, t. 6, figs. 14 — 15. 



Of this species I have examined 14 young specimens (Kroyers original ones), of which 12 belonged to pernultimate 

 stage and a single to stage IV. They were all rather mutilated, but nevertheless it is scarcely doubtful that Poppe's and 

 Giesbrecht's rather imperfect descriptions refer to this species. Total length is 8-6 (7-0 -j- i-6). Shape of the head is alike 

 Giesbrecht (fig. 14—15); the lateral corners are rounded and not produced. The antennulae extend with the 25 segment 

 beyond the end of the abdomen. The segment 8 co 9 are only indistinctly separated and together just as long as the segment 

 21, which is 115 as long as the segment 22. The latter is i*i as long as the 23 and 25 segment, which is 1.3 as long as 

 the 24. The mouth-appandages scarcely provide features of interest. The Ri of pes I— IV possess no Si The Re III pes II 

 is by the Se I divided into a proximal shorter and a distal almost 12 as long; the exopodites of the three last pair of legs 

 are wanting. The inner margin of the first basipodite of the fifth pair of legs is smooth. 



