10 J Canadian Arctic Expedition, 1 913-1 8 



little doubt, makes it a synonym of gigas Glaus, which was distinguished from 

 viridis only by its size. E. B. Forbes considers ingens as synonymous with 

 viridis. It might be assumed as probable that the form of the arctic collections 

 which has been called magnus was ingens or gigas, but the form of the receptacu- 

 lum seminis precludes this determination, and has made the use of a new name 

 necessary. 



Something might be said in regard to the use of *"the spines of the .swimming 

 feet in specific determinations. Schmeil considers these of no value because of 

 what he considers their great variability. It is true that variations may be 

 found. I have found in the same collection one with the formula for the ter- 

 minal segments of the swimming feet 2, 3, 3, 3, and another 3, 4, 4, 4. I have 

 even found an individual with the right fourth foot differing from the left; yet 

 these variations are so rare that they may almost be considered as abnormalities. 

 Practically all the individuals from a collection will have the same armature, 

 and this condition is so constant as to characterize the collection. It is a 

 characteristic to be reckoned with in any specific description. 



It may be added that the true C. viridis appears to be very rare in America. 

 It is not clear that Forbes had it at all. Chambers, 1912, states that he had it 

 from Edgewater, N.J. In our collections the only positive evidence was from 

 a collection near Green Bay, Wisconsin, and one from Polk county, Florida; 

 these specimens were typical in the armature of the swimming feet and the 

 form of the fifth foot and of the receptaculum seminis. 



Of the forms of the type of C. viridis, C. americanus is the most widely dis- 

 tributed in America. C. brevispinosus is, for the most part, a limnetic form, 

 found in the larger bodies of water. C. parcus is comparatively rare. It may 

 be an open question whether C. gigas is found in America; it is very possible 

 that the indentifications of gigas and ingens by other authors should be consid- 

 ered as giving localities for the proposed new species, C. magnus: Herrick's 

 figures were not always accurate, and little attention was paid to the form of 

 the receptaculum seminis by the earlier authors. Probably C. magnus will be 

 found to be characteristic of the colder waters. 



Cyclops strenuus Fischer. 

 Plate IV, figs. 2, 3, and 7. 



This was, perhaps, the most common form of copepod found in the col- 

 lections of the expedition. It was found at Cape Bathurst, July 26, 1916, and 

 in collections made at Bernard harbour, July 4, 1915, November 28, 1915, 

 February 28, 1916, May 6, 1916, May 21, 1916, May 26, 1916, and June 13, 

 1916. In the collections of February 28 and May 6, they were immature, but 

 egg-bearing females were found in the collection of May 21. 



This species is discussed in Marsh, 1912, and its synonomy indicated. 

 Sars, 1913, has been published since the appearance of Marsh's paper, and in that 

 work C. abyssorum, C. lacustris, and C. scutifer are separated from C. strenuus. 

 The characteristics which separate these species from C. strenuus are difficult 

 to recognize, and do not appear to have even varietal value. In the opinion 

 of the present author these names should be considered as synonyms. 



The specimens of this expedition correspond very closely, in structure, to 

 those found in other localities. PL IV, fig. 2, shows the abdomen; PL IV, fig. 3, 

 a furcal branch, and PL IV, fig. 7, a fifth foot. 



The hyaline lamella of the terminal segments of the antennae was not evident 

 in these specimens. The cuticular ridge of the furca was not universally present. 

 Moreover, the inner margin of the furca was ciliated in some individuals but 

 not in others. The receptaculum seminis is of the typical circular form. Sars, 

 1913, states that the egg sacks are oval in form, while in the figure of Schmeil, 

 1892, they are elliptical. In the specimens of this expedition they were spherical. 



