4 j Canadian Arctic Expedition. 1918-18 



macrurus. PL I, fig. 5, shows the first foot, and PI. I, fig. 6 shows the fourth 

 foot. PI. I, fig. 7 shows the fifth foot of the female. 



The left male fifth foot, shown in PI. I, fig. 8, is like that of L. macrurus. 

 The exopodite of the right male fifth foot consists of three segments; the second 

 segment has the customary spinous prolongation from the inner distal angle, 

 and a hook-like spine on the outer distal angle. The third segment, situated 

 just within the outer spine, is one-third to one-half the width of the sec* did 

 segment, is digitate, curved towards the inner margin of the foot, pointed at 

 the extremity, and bears upon its dorsal surface a curved spine. It is distinctly 

 separated from the second segment by a joint. 



Average length exclusive of furcal setae: females 2.99 mm., males 2.6 nun. 



This species was found only in the collections made at Oollinson point, 

 Alaskan Arctic coast, October 10, 1913, as a limnetic form under 10 inches of ice 

 in a pond 4 feet deep on the coastal tundra. It is to be presumed that moi 

 tensive collections may show a wide distribution in the northern waters. 



Limnocalanus johanseni is readily distinguished from L. macrurus by the 

 much shorter furcal rami which are armed only with fine cilia on the inner border 

 and not covered with small spines or coarse hairs as in the former species. 



Four species of Limnocalanus have been described, macrurus Sars, sinensis 

 Poppe, sarsii Daday, and grimaldii Guerne. Sinensis and sarsii are quite differ- 

 ent from the other species in the structure of the male fifth feet, and Ekman 

 (1905) has made the genus Gigantella for sarsii, while Burckhardt (1913) has 

 proposed the genus Sinocalanus for sinensis with the species sinensis Poppe, 

 dorrii Brehm, and mystrophorus Burckhardt. In macrurus and grimaldii the 

 structure of the male fifth feet is almost the same and in both the third segment 

 of the right exopodite is indicated by a small tubercle on the second segment. 

 The existence of a distinct third segment in johanseni separates this species 

 definitely from the others. 



Genus Eurytemora. 



Specimens of Eurytemora were found in the collections made at the following 

 localities: Teller, Bering strait, Alaska, August 3, 1913; Martin point, Arctic 

 coast of Alaska, July 28, 1914; Herschel island, Yukon territory, Canada, 

 August 13, 1914; Bernard harbour, September 23, 1915; Bernard harbour, 

 Oct. 6, 1915; Bernard harbour, Nov. 28, 1915; Bernard harbour, July 3, 1916; 

 Bernard harbour, July 14, 1916. Most of the material was so immature that 

 it was impossible to make specific determinations. In the collection of Sep- 

 tember 23, 1915, from a brackish pond 4 feet deep, at Bernard harbour, how- 

 ever, there was a large number of mature specimens of both sexes. It is from 

 these that the following description is made. 



Eurytemora canadensis, n. sp. 



Plate I, figs. 9-12. Plate II, figs. 1, 2, 4, and 7. 



FEMALE. The cephalo-thorax is oval in outline, the greatest width being 

 forward of the middle. The last segment extends backward somewhat on the 

 sides of the first abdominal segment, but is not produced laterally; the outer 

 border of this segment is armed with a few minute hairs. The outline of the 

 cephalothorax is shown in PL I, fig. 9, and the outer border of the last segment 

 in PL 1, fig. 12. The first segment of the female abdomen, shown in PL I, fig. 11, 

 is somewhat expanded laterally, being about a third wider in the middle than 

 at the ends. The first and third segments are of about the same length, and are 

 one and one-half times the length of the second. The furcal rami are slender, 

 about equal in length to the first two abdominal segments, and are ciliate on 

 both inner and outer margins, except on that part of the outer margin distad 

 of the lateral seta; these hairs are not only on the margin, but are present on 



