90 
about one-fourth the size of the ovary. Hach vas deferens 
courses posteriorly into the oval genital segment. It com- 
municates with the sac of the spermatophore on the external 
margin near the posterior end. <A short cement gland 
furnishes a duct which passes in at the anterior end of 
the sac. The spermatophore, an oval body containing 
the spermatozoa, is expelled from an opening near the 
posterior angle of the segment. 
In Lepeophtheirus the fertilisation of the female is 
accomplished soon after the “chalimus” stage 1s com- 
pleted. The genital segment is then very small, about 
one-fifth the length of that of a mature female. It is 
grasped by the male on the dorsal aspect. The antennz 
close round the junction of the genital segment with the 
fourth thoracic, and the second mavillipedes seize the 
segment immediately in front of its junction with the 
abdomen. ‘The animals remain in this condition for some 
time, and can only be separated with difficulty. The 
spermatophores are discharged in pairs. When they are 
ready for discharging the male folds the whole of the 
posterior portion of its body along the ventral surface of 
the female. The openings of the spermatophore sacs are 
thus brought in contact with the vulve. The spermato- 
phores are then discharged, and being in a viscid condi- 
tion, at once stick to the female. One end of the cover- 
ing, probably the last part that leaves the opening, is 
drawn out into a fine thread, which helps to secure the 
spermatophore. The spermatophores are not, apparently, 
always fortunate in reaching the vulve. It is by no 
means uncommon to find them planted amongst the 
appendages in little clusters ike grapes. These have 
been mistaken by some of the earlier Zoologists for the 
eggs, when the true egg sacs were considered to be 
antennules. 
