306 University of California Publications in Zoology |Vou.9 
The hauls are so few (fifteen) for which temperatures are 
known where Metridia was taken, that it is useless to try to 
draw conclusions as to the effect of those factors in the distri- 
bution of the species. It may be stated, however, that it 
occurred at the surface when the temperatures ranged from 
14°7 to 20°5, and at salinites from 33.577 to 33.856. As is 
the case with the two preceding species, I find it impossible 
to separate the temperature and light effects. The abundance 
varied from nearly 12,000 per hour at 19° between the hours 
of 10 and 12 p.m., to 8 per hour at a temperature of 19°2 
between 4+ and 6 a.m. Hauls 1875 to 1892 inelusive in table 3 
form an interesting group if it is desired to note how abund- 
ance varies with the time of day while the temperature is 
practically stationary, there being a range of only 023. 
Farran (1910, p. 67) gives the vertical range of Metridia 
lucens as from 0 to over 2000 meters, and mentions the marked 
tendeney to swarm at meht at the surface. The region of 
ereatest abundance during the day is between 50 and 100 
meters (about 27-55 fathoms). This is far above the depth 
of the daylight plurimum for this species according to our 
results. The difference is probably due to the different depth 
to which light penetrates in this region as compared with that 
covered by the International Council (see Hjort, 1910, p. 505, 
and the discussion at the end of this paper). 
The other species found at the surface are listed in table 
32 which gives their ranges in fathoms. Each of the ten species 
was more or less abundant at the surface, and since they are 
the less common ones they form a group which may conveniently 
be considered alone. The depths given for the vertical closing 
nets are upper and lower possible limits; the open vertical net 
did not take specimens in hauls that began above the indicated 
depths. 
