218 BULLETIN OF THE BUREAU OF FISHERIES 



there were only about 2 per cent of C. hyperboreus, less than half its percentage 

 in the verticals. In the two instances when the percentage rose to 25 and 30 per 

 cent, 500 and 150 copepods of all kinds were taken — that is, only 125 and 45 C. 

 hyperboreus, respectively. It has been detected in only one surface haul in the gulf 

 for July, August, or September — that is, off Cape Elizabeth on August 14, 1913 

 (station 10103; see Bigelow, 1915, p. 293), a locality where the surface tempera- 

 ture was comparatively high (16.11°) and where it was probably brought up to the 

 top of the water by vertical currents. The date when it abandons the uppermost 

 stratum can not be stated, no data being available on this for the May and June 

 cruises of 1915, but probably its sinking is induced by the vernal warming of the 

 surface water. 



Relationship to temperature and salinity. —As might be expected from its polar 

 origin, C. hyperboreus occurs in greatest number and is most regularly distributed 

 in the gulf in comparatively low temperatures, the great majority of the spring 

 (February to May) records being from temperatures of 1 to 5°. It is doubtful 

 whether any of the specimens taken in June were actually living in water warmer 

 than 7°, and most of the few captures in the later summer have been in horizontal 

 hauls at depths where the temperature ranged from 4.8 to 8°, only one of them in the 

 much warmer surface stratum. The highest temperatures in which the presence of 

 C. hyperboreus is definitely established, apart from the one capture on the surface 

 just mentioned (p. 217), are 9 to 10°, 17 a temperature in which probably it could not 

 long survive. 



If C. hyperboreus actually does succeed in breeding in the western side of the 

 gulf in spring and early summer, probably it does so exclusively in temperatures 

 lower than 3 to 4°, the range of temperature at the rich March and April stations 

 (stations 20087 and 20090, fig. 69) being from 2.25 to 5.09°, and the comparatively 

 large numbers taken there on June 26, 1915 (station 10299), may be explicable as 

 resulting from spawning some weeks or months previous when the temperature was 

 no higher than that. The richest immigrations of C. hyperboreus into the gulf so 

 far encountered have been in temperatures falling between 1.9 and 4.6°. It is not 

 probable that the distribution of C. hyperboreus is influenced by variations in salinity 

 within the limits prevailing in the open waters of the Gulf of Maine. 



Candacia armata Bceck 



This large and powerful species may be recognized by the asymmetry of the 

 posterior part of the body, the genital segment being irregularly dilated in the mid- 

 dle, and the first segment of the abdomen having a sac-shaped dilatation turned toward 

 the right side. The frontal margin between the bases of the antennae is squarely 

 truncated, also. It has been recorded from the coast of Norway, the British Isles, 

 the Mediterranean, the North Atlantic, and the Indian Ocean (Scott, 1911), while 

 Esterly 1S (1905, p. 194) described it as "rather common" at San Diego, Calif. The 



» OS Penobscot Bay, Aug. 4, 1913, station 10101, temperature at 50 meters about 9.3°; ofl Seal Island, Nova Scotia, Sept. 2, 

 1915, station 10311, whole column of water, surface to bottom, 9.4 to 10.1°; ofl Machias, Me., Oct., 9, 1915, station 10327, whole 

 column 9.4 to 9.8°. 



11 As C. pcctinata Brady. 



