Fresh water Copepoda 5 J 



the body of the furcse. PL II, fig. 1 shows the furca enlarged. The antennae 

 have the typical structure of the genus and extend nearly or quite to the fourth 

 cephalothoracic segment. The structure of the swimming feet is typical. PL I, 

 fig. 10 shows the fourth foot. It is somewhat interesting that in the case of 

 the individual from which this was drawn the companion fourth foot had five 

 setae on the terminal segment of the endopodite instead of the regular number, 

 six. The second segment of. the fifth foot has a seta about midway of its outer 

 margin. The third segment is about one and a half times as long as the first 

 and bears a long spine at about midway of its outer border and another at its 

 outer distal angle ; the inner distal angle is prolonged into an unguif orm process, 

 which projects at an angle of forty-five degrees with the axis of the segment; 

 the distal border of this process is armed with a variable number of teeth, as 

 many as eleven having been counted. The fourth segment is one-half as long 

 as the third and bears a spine at its inner distal angle and a long terminal spine. 

 PL II, fig. 2 shows the fifth foot. 



MALE. The form of the male cephalothorax is like that of the female, but 

 is somewhat narrower and more elliptical than oval in outline. The cephalo- 

 thoracic appendages, with the exception of the fifth feet, are those typical of 

 the genus. The abdomen, PL II, fig. 4, is slender, the segments being about 

 equal to each other in length. The furcal rami equal in length the three pre- 

 ceding segments; the inner margin is ciliate and the outer very sparsely so; 

 the hairs are much finer than those on the female furca and are comparatively 

 few in number; the fifth foot is shown in PL II, fig. 7. The right foot is dis- 

 tinctly four segmented. The left foot terminates in two finely ciliated prom- 

 inences. 



Length, exclusive of furcal setae: males 1.95 to 2.1 mm., females 1.9 to 

 2.25 mm. 



It is very probable that some of the immature forms collected in other 

 localities belong to this species. The single individual collected at Herschel 

 island, however, was not E. canadensis, and does not correspond to any other 

 described species. In the absence of more material it does not seem wise to 

 attempt a description of it. 



Granting that trie immature individuals were probably E. canadensis, it 

 appears, from the fact that most of those collections were made earlier than this 

 one of September 23, that this species matures in the late fall. 



Heterocope septentrionalis Juday and Muttkowski. 

 Plate II, figs. 3, 5, 6, 8-13. 



This species was described by Juday and Muttkowski in 1915, pp. 27-30, 

 fig. 4, A, B, C, D, E, and F, fig. 5, A, B, and C, fig. 6, A and B, from material 

 collected at St. Paul island, Alaska, and, as stated by them, undoubtedly differs 

 from the species previously described. The forms collected by the Canadian 

 Arctic Expedition differ only in certain minor details which should be considered 

 as variations within species limits. The female abdomen is shown in PL II, 

 fig. 3. The processes of the genital area of the first abdominal segment are 

 described and figured by Juday and Muttkowski as " trilobate." The specimens 

 examined in these investigations have shown much variability in the form of 

 these processes. They have been found trilobate as shown in PL II, fig. 10, 

 indistinctly trilobate as in PL II, fig. 11, and bilobate, as in PL II, fig. 12. In 

 the fifth foot of the female shown in PL II, fig. 5, the teeth of the inner margin 

 of the terminal segment are distinctly serrate. 



The abdomen of the male is shown in PL II, fig. 6. The external spines of 

 the right exopodite of the second foot are distorted, as in the figure of Juday and 

 Muttkowski. This is shown in PL II, fig. 9. The spine of the first segment of 

 the right exopodite is shown in PL II, fig. 13. The fifth feet of the male, shown 



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