526 U. S. BUREAU OF FISHERIES 
less than 1.35 millimeters. The total absence of cleavage stages 
at this station (the earliest eggs having the embryo well developed) 
indicates that they may have been carried for a long distance or 
belong to an entirely different race of fish. The force of the Lab- 
rador current at this point, the low temperature, and the number 
of planktonic forms that occur here and at no other station tend to 
substantiate the former possibility. 
Although the significance of the differences of the means has not 
been determined statistically, it appears, on the basis of the collec- 
tions alone, that temperature has a decided effect on the size of cod 
eggs, causing them to average larger during the colder periods and 
decrease in size as the water becomes warmer. Thus in Massachu- 
setts Bay eggs averaged smallest in December and May and largest 
in February. In the region of the Labrador current the largest 
average was found at the northernmost station and the smallest at 
the more southerly ones when the summer warming of the water 
had become noticeable. In the North Sea a similar condition was 
noted by Ehrenbaum, who found cod eggs averaging 1.46 milli- 
meters in January and 1.3 millimeters in April. 
Following are the average sizes of 50 cod eggs taken in Massa- 
chusetts Bay at various times: 
Date Millimeters 
PSC MAM, ODA sesh PEE Pl Te a, OTP Sa a TN er 1. 458 
4 WMG@CAMi NODE # has tax re yest ty etek Ta oy see raphe eee ae eed ees Pe ee 1. 495 
PCT S(t US Pe aS SE ee SE a, eA SMW CRU terty 99, ay fio 2 1. 494 
UENCE) OR} IS Pets ts a Sn a eNO ed eR ee LA Ae OS 1, 529 
IN (Gi cela If 6 Yaa A tye ee alan RS ee ME AA ao eh EB ba eB a i 1. 501 
ASO SY Stal G26 As eed Cb es: eat As Rebel BA) oR ea eee Ed ee le 1. 518 
May 20 li O25 tutes Ay A eye Ne. eh ec ee 1. 488 
The average size of cod eggs from the Grand Banks in June, 1924, 
was 1.2 to 1.3 millimeters; from the polar current in June, 1924, 
1.42 millimeters; and from Massachusetts Bay on June 5, 1926, 1.425 
millimeters. 
Experiments were carried on at Gloucester and on the Boars Head 
fishing grounds to determine whether the seasonal fluctuations in the 
average size of cod eggs are due to temperature. In general the re- 
sults appear to be significant, the eggs fertilized at 0° C. averaging 
1.447 millimeters and those fertilized at about 8° C. averaging 1.4106 
millimeters. The increase in size at a reduced temperature corre- 
sponds with the observations made on eggs taken in the field. 
The investigation in Massachusetts Bay was not confined to the 
young of the cod, haddock, and pollock, but included eggs and larvee 
of all other species taken with them. 
There are at least 61 species of fishes that either have been taken 
in their larval forms about Woods Hole or may be expected in col- 
lections there. Thus far a bibliography for each species has been 
gathered, including original illustrations and notes on distribution, 
and the missing links in developmental histories have been listed. The 
collections are being searched at present to fill these gaps. 
MACKEREL 
During 1926, the investigations on the mackerel fishery, in co- 
operation with the division of fishery industries, were continued by 
