THE AMERICAN LOBSTER. 
43 
during tlie latter half of July and the lirst two weeks ol August. The summer 
spawning of each year lasts about six weeks, but may fluctuate from year to year, 
backward or forward through an interval of a fortnight. 
The observations for the years 1890 and 1891 only, are large enough to make a 
comparison of much value. Of the 86 lobsters with new eggs examined in July and 
August, 1890, 85 per cent extruded eggs in July and 15 per cent in August, while in 
the following year, out of 38 females, one-half had laid in July and half in August. 
In 1890, however, 72 per cent of the eggs were laid in the latter half of July and 15 
per cent in the first half of August, while in 1891 47 per cent were extruded in the 
first part of August, and 31 per cent in the latter half of July. The season of 1891 
thus appears to have been somewhat later than that of the former year. 
The record of ocean temperatures given in table 2 (p. 25) shows that the water 
was cooler in 1S91 than in the preceding year, the difference of the mean annual 
temperatures being 1.6°. This difference is slightly raised by eliminating the month 
of June, when the smallest number of lobsters carry eggs. It is possible that so small 
a variation as is here recorded in the mean aunual temperature of the sea water would 
sensibly affect the rate of development, yet a larger number of observations ivould be 
required before this could be satisfactorily shown. 
There are undoubtedly other causes than the temperature changes which influence 
the growth of the ovarian eggs, which it must be remembered require at least two 
years to reach maturity. Anything which affects the individual during this interval 
may affect also the time of spawning, and this affords a partial explanation of the fact 
that eggs are sometimes produced at other seasons of the year than the summer. 
SUMMER EGGS ON THE COAST OF MAINE. 
Tables 8, 9, and 10 throw more light on the time of spawning upon the coast of 
Maine, where the water is somewhat cooler than at Woods Hole. The range of tem- 
perature in the Gulf of Maine is about the same as that obtained at Pollock Rip 
light-ship, off the southern end of Cape Cod, namely, 32° to 62° F. 
Table 8. — Time of spawning at Southport , Maine. 
[Many of the lobsters were captured in Nova Scotia and brought to Southport before laying their eggs.] 
No. 
Place of spawning. 
Date of 
exami- 
nation of 
eggs. 
Stage of development. 
Age 
of em- 
bryo. 
Date of 
extrusion 
of eggs. 
1 
2-3 
Southport, Me 
1893. 
Sept. 7 
Telson in front of optic lohes : Eye-spots oval 
Days. 
61 
35 
July 8 
Aug. 3 
Aug. 5 
4-8 
do 
33 
9-10 
30 
11 -1G 
29 
Aug. 9 
Aug. 11 
17-21 
do 
27 
22-23 
do 
25 
Aug. 13 
24-25 
do 
18 
Aug. 20 
