302 
bulletin of the bureau of fisheries. 
section of the sternum of the eighth thoracic segment. The divergent wing-like processes 
in front of the annulus in the crayfish evidently correspond to the convergent wings, 
which are the modified sternum of the seventh thoracic somite, and which, united with 
the middle piece, form the elastic lips of the shield-shaped receptacle in Homarus 
C St • XIII, fig. 4 ). 
The laying of eggs in the crayfish may not occur for some weeks after sexual union, 
and as Andrews remarks, some protection such as the annulus affords is necessary, since 
sperm can not long survive exposure to water. 
PAIRING HABITS IN THE LOBSTER. 
Both Boeck ( 24 ) and Fraiche ( iog ) have referred to the union of the sexes in the 
European lobsters as if they had witnessed the act, but the errors which they exhibit 
tend to discredit their statements, however brief. Fraiche remarked that copulation 
in both the common and Norwegian lobsters took place in fall (October and November), 
and in the case of the former that it was extended into winter. “As with the crayfish, 
the sexual act is accomplished belly to belly, and so closely 'and firmly do they clasp 
each other, that, if taken from the water at this period, it is with difficulty that they 
can be separated.” 
But the only reliable observations under this head have been made by Anderton (5), 
of the Marine Department of New Zealand. The sexual act was noticed on a number 
of occasions among the European lobsters kept under observation in small artificial 
ponds. The general succession of events was as follows: Molting in early summer 
(November and December), followed in the course of a few hours by coition between a 
soft female and a hard male, and by the laying of eggs about two months after this 
event. 
One of the female lobsters kept under observation by Anderton molted on Novem- 
ber 21, at 3 p. m., and lay for some time beside her cast shell. “Two hours afterwards,” 
to continue his account, “it was seen roaming round the pond and frequently approach- 
ing the various shelters, returning regularly and fearlessly to a shelter containing a large 
male. On approaching the entrance to this shelter the large claws were extended in a 
direct line with the body and the antennae were thrust within the shelter. After a few 
moments the rostrum of the male appeared, the female meanwhile rapidly whipping 
her antennae across the now projecting rostrum of the male, which in turn showed increas- 
ing signs of excitement, the antennae being whipped very rapidly over the female in the 
same manner. After an interval of perhaps a minute the male gradually withdrew 
from his shelter, the female at the same time turning over on its back. Coition took 
place at once, the act occupying only a few seconds, the male retiring at once to its own 
shelter and the female into another. The following day both were observed to be living 
in one shelter, and they continued to do so, on and off, for several weeks.”® 
a In reply to certain specific questions regarding the pairing of lobsters, Mr. Anderton has kindly written under date of 
August 2i, 1910, as follows: “ The female lobster after casting does appear to seek out a male as soon as the distressing effects of 
molting have somewhat worn off. Male and female have frequently been observed living in one shelter for some days and even 
weeks after coition. The act of coition is very brief, and will not occupy more than half to a whole minute. They copulate, as 
you express it, “belly to belly,” and head to head. The large chela? do not come into use during the act so far as I have observed. 
The female voluntarily turns over almost completely onto her back, the excited male completing the process for her.” 
