436 
BULLETIN OF THE BUREAU OF FISHERIES 
on the Halcyon cruise in 1920 and 1921; but, as pointed out above (p. 396), a com- 
paratively rich collection of Cbsetoceras was made in Ipswich Bay on January 30, 
1913 (see also Bigelow, 1914a, p. 405). 
According to McMurrich (1917, and unpublished notes), the genus Cbsetoceras 
as a whole is scarcest at St. Andrews during the winter and most abundant between 
mid-June and September. Fritz’s (1921) more detailed counts of the several species 
of Chsetoceras combined, at the same locality, show constantly increasing numbers 
from the middle of March through April and May, with very abundant flowerings 
in July and August followed by a decrease during the autumn to the midwinter 
minimum, when the genus was so scarce that on two occasions (December 27 and 
January 13) none at all were detected. 
McMurrich’s, Bailey’s (1915 and 1917), and Fritz’s lists for St. Andrews, com- 
bined, comprise the following species: Ch. boreale, Ch. constrictum, CTi. contortum, 
Ch. convolutum, Ch. crinitum, Ch. criophilum, Ch. danicum, Ch. debile, Ch. decipiens, 
Ch. diadema, Ch. laciniosum, Ch. sociale, Ch. teres, and Ch. willei. Ch. debile begins 
flowering actively there in April and May, is far the most important species numeri- 
cally, and was chiefly responsible for the very rich Chastoceras flora of July and August 
recorded by Fritz. Ch. sociale, which yielded her next largest counts, was practically 
nonexistent in November, December, January, February, and March; appeared in 
April; flowered actively (207,500 per haul) in May; vanished in July; reappeared 
in August; and attained its maximum abundance (280,000 per haul) on September 6. 
Ch. diadema and Ch. laciniosum have been found at St. Andrews from late winter 
through spring, summer, and early autumn, both of them having their plurimum in 
July. Ch. decipiens has been found sparsely represented at St. Andrews in late 
June, July, August, September, October, and early November, and the various other 
species only between early July and the last week in October. The most notable 
difference between the status of the genus Chsetoceras at St. Andrews, as contrasted 
with the open gulf, is the scarcity of oceanic species. Ch. atlanticum and Ch. densum 
have not been detected there at all. Fritz found C. criophilum in only one haul 
on October 12 at St. Andrews. It is also interesting that in 1917 Ch. constrictum did 
not appear in Fritz’s lists at St. Andrews until July 17 — i. e., about a month later 
in the season than on the other side of the Bay of Fundy in 1920 (p. 435). Fritz 
(1921, p. 53) has remarked that the greatest number of species of Chsetoceras was 
recorded for September, though the plurimum for the genus as a whole and for its 
two most numerous species fell in August. Fish (1925) reports 20 species ofChse- 
toceras at Woods Hole, but only two of them — decipiens and didymum — were plentiful 
enough in his catches ever to be classed as “abundant.” These two showed a suc- 
cession of maxima in winter, summer, and autumn; not, however, in spring. 
Coscmodiscus 
The genus Conscinodiscus is very widely distributed in the Gulf of Maine, 
both in time and space. In midwinter, on the whole, it is the dominant genus of 
diatoms, both at St. Andrews (McMurrich, 1917; Fritz, 1921) and along the northern 
and western shores of the gulf generally as off Cape Cod; for example, in Massa- 
