484 
PACIFIC SCIENCE, Vol. XXI, October 1967 
TABLE 2 
Species in the 350-250 m Layer, Partially Coincident with the 
Deepest Scattering Record (Daylight) 
CONCENTRATION OF INDIVIDUALS PER 10,000 M 3 OF WATER FILTERED 
GROUP 
GREATER 
THAN 5,000 
4999-500 499-50 
LESS THAN 50 
Chaetognatha 
S. bierii 
S. decipiens 
S. scrippsae S. maxima 
K. subtilis 
S. bipunctata 
S. euneritica 
S. hexaptera 
S. minima 
S. pacific a 
S. zetesios 
Siphonophorae 
Ch. appendiculata 
L. multi crist at a 
L. conoidea 
N. dubia 
St. rubra 
Ph. hydrostatica 
B. elongata 
Medusae 
S. coccometra 
L. tetraphylla 
C. alba 
C. brunnea 
1550 hours on 
5 September 1965, 
bright and depth of 218.40 m it was 
36.40 m thick. The 
at 91 m, 200 m, and 345 m. The species ob- 
served coincidently are detailed in Tables 1 
and 2. 
The nighttime scattering layer at 2038-2345 
hours on 3 September 1965 appeared to be 
54.60 m thick at the upper levels, and at a 
species observed coincidently are detailed in 
Tables 3 and 4. 
The siphonophores considered to be most 
probably responsible for the production of 
scattering are the Physonectae, those with floats 
containing gas (CO). Species of that group 
( Stephanomia bijuga, St. rubra, and Physo- 
TABLE 3 
Species in the 100-20 m Layer, Partially Coincident with the 
Shallower Scattering Record (Night) 
CONCENTRATION OF INDIVIDUALS PER 10,000 M 3 OF WATER 
FILTERED 
GREATER 
GROUP 
THAN 5,000 4999-500 
499-50 
LESS THAN 50 
S. bierii 
S. euneritica 
P. draco 
S. hexaptera 
S. enfaia 
Chaetognatha 
S. minima 
S. pseudoserra- 
todentata 
M. atlantica 
A. ernesti 
Siphonophorae 
E. spiralis 
Ch. appendiculata 
N. reticulata 
Medusae 
L. tetraphylla 
S. geometrica 
C. peregrin a 
Ctenophorae 
Beroe spp. 
