CAXADIAX FISHERIES EXPEDITIOX, nu'rl.j 465 



ill uumbers about the middle of that period. From 9 a.m. to G p.m. it seeks a lower 

 level. The individuals obtained on this cruise were of large size. 



The Princess cruise (stations 3 to 26) gives similar results, but the figures require 

 analysis: 9 p.m. and 12 midnight show many large individuals at the surface (stations 

 8 and 9; 6 a.m. shows several only (stations 10 and 20). For some reason the single 

 3 a.m. station (19) is negative. From 9 a.m. to 6 p.m. the stations are negative or 

 show only small individuals (9 a.m., ICmm. ; 12 midnight, 5-7mm. ; 3 p.m., 6mm.); 

 but there is a single exception at station IG, where one large individual was obtained. 



The specimens from the second cruise of the Acadia (stations 37 to 90) have been 

 divided into two groups, those under and those over 20mm. in length. The larger group 

 is represented in surface hauls in only three instances. A few specimens were obtained 

 in the surface hauls of the first three stations, at 6 p.m., 9 p.m., and 12 midnight. The 

 largest individuals were obtained at the midnight station. In the deeper tow hauls of 

 the latter i^art of the cruise, they were obtained in only three instances; occasional in 

 one at 9 a.m., abundant in one at 9 p.m., and one at 12 midnight. 



Those under 20 mm. show a different distribution. Surface hauls : 9 a.m., two 

 negative, one positive (occasional specimens up to 10 mm. long) ; 12 m., one negative, 

 two positive (occasional specimens up to 9mm.) ; 3 p.m., one positive (many specimens 

 up to 13mm.) ; G p.m., two positive (very many specimens up to 19mm) ; 9 p.m., three 

 positive (very many specimens up to 16mm.) ; 12 midnight, three positive (many 

 specimens up to 20mm.) ; 3 a.m., four positive (several specimens up to 18mm.) ; 6 

 a.m., one negative, two positive (occasional specimens up to 11mm.). Deeper tow 

 hauls : 9 a.m., one negative, one positive (occasional specimens) ; 12 m., one negative, 

 one positive (occasional specimens) ; 3 p.m., one negative, two positive (many speci- 

 mens) ; 6 p.m., one positive (very many specimens) ; 9 p.m., three positive (very many 

 specimens) ; 12 midnight, one positive (many specimens) ; 3 a.m., one positive (occa- 

 sional specimen) ; 6 a.m., one positive (very many specimens). There is little evidence 

 of any daily migration of the larger individuals at these stations. They remain almost 

 constantly in the depths. The smaller individuals come nearer to the surface. They 

 are less abundant and smaller or entirely absent from 6 a.m. to 3 p.m. 



Taking the shallow vertical hauls (30 to metres) of the second Princess cruis'j 

 (station 27 to 50), we have the following upper limits in size for the individuals 

 obtained in the several three-hour periods: 9 a.m., 15mm.; 12m., 18mm.; 3 p.m., l(3nim. ; 

 6 p.m., 20mm. ; 9 p.m., 26mm. ; 12 midnight, 28mm. ; 3 a.m., 20mm. ; 6 a.m., 20mm. 

 There would seem to be a definite movement of the larger individuals across the 30- 

 metre line during the twenty-four hours. 



As to the effect of temperature on the vertical distribution, we may compare ths 

 early and late cruises both outside and inside the gulf. On the earlier cruises the 

 surface water was decidedly colder than on tlie later ones. The Acadia^s cruises show 

 that outside the gulf in May-June large individuals came in numbers to the surface 

 during the night, while in July-August tliey were virtually absent. The Princess' 

 cruises show that inside the gulf in ,lune larger individuals came to the surface than 

 came above 30 metres in August, for 9 a.m., 12m., 9 p.m., 12 midnight and 6 a.m. This 

 decrease in the daily vertical migration is doubtless due to the warming of the surface 

 water. 



The facts point to the following conclusions Safjitta elegans is confined to water 

 of comparatively low salinity, being stopped in its migration into the depths by water 

 of high salinity. It is affected by light, coming nearer the surface at night. It is 

 affected by temperature, keeping to the colder water. The young behave differently 

 from the adults, living in the lighter, warmer surface water. With increasing age it 

 becomes gradually restricted to the darker, colder water, which is deeper. 



