176 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 112 



may remove debris from among the eggs of Gallianassa and, if so, it 

 may also help to keep the gill-chamber clean. It is hoped that further 

 collecting and possibly experimental work will make clear the host 

 preferences and relations with the host of this copepod. 



Immature specimens occasionally are found in debris from pre- 

 served Gallianassa; the smallest corresponds to the second copepodid 

 stage in other copepods. It is possible that the early stages are free 

 living and dispersive, development only being completed when a host 

 is found. 



Hemicyclops purpureus Boeck 



Hemicyclops purpureus Boeck, 1873, p. 42; etc. 



This species was reported by Wilson (1936, pp. 368, 375) from 

 plankton collected in Fox Channel (lat. 66-67° N., long. 80° W.), 

 northern Canada, by Captain R. A. Bartlett in August 1933, but no 

 diagnosis or figures are given. Taking into account both the restricted 

 range otherwise known for purpureus (coasts of Norway, Sweden, and 

 possibly Scotland) and Wilson's lapses in descriptions of other species 

 in this genus, I do not think that his record can be accepted at present 

 entirely without question. If correct, however, his record would be 

 of great interest, and it is hoped that further collections in that area 

 will confirm his identification. Such confirmation is unfortunately 

 impossible now since the specimen (or specimens) that he examined 

 are not in the U.S. National Museum, where the Bartlett collection 

 was deposited (letter from Dr. T. E. Bowman, November 21, 1957). 



Because I have not examined specimens, no other account of 

 purjmreus is given here and it is not included in the key. On the basis 

 of Sars' redescription (1917), the species apparently differs from 

 thy&anotus in the proportions of the caudal rami and of the fifth legs 

 and in the armature of the third segments of both rami on the fourth 

 swimming leg. It may readily be distinguished from adhaerens, 

 subadhaerens, elongatus, and arenicolae by the presence in these of the 

 following: 6-segmented urosome, reduced mandibular setation, 4 

 simple terminal elements on the maxilla, shorter maxillipedal process 

 (of the female) and different armature of the swimming legs. 



Hemicyclops adliaerens (Williams) 



Figures 3, d-j; 4 



Lichomohjus adhaerens Williams, 1007, pp. 75-70, pi. 2. 



Hemicyclops adhaerens, Wilson, 1932a, pp. 345-346, fig. 206. — Light and Hartman, 



1937, pp. 179, ISO— Scwell, 1949, p. 67. 

 Hemicyclops americanus, Wilson, 1932b, pp. 44-45, pi. 5, figs, a-h.- — Light and 



Hartman, 1937, pp. 179, ISO.— Nicholls, 1944, p. 45.— Sewcll, 1949, pp. 



67-69. 



Types: Williams (1907) stated that his specimens were from 

 "Wickford, very abundant under small stones between tides." He 



