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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I37 



with the ejection of a Httle secretion from the cement gland of the 

 genital apparatus, which will detach the remaining empty egg capsules 

 from the last hatch. At this time the Caligus female undergoes severe 

 birth pangs, with violent convulsive contractions of the whole body, 

 and the claws of the different appendages which are inserted in the 

 skin of the fish deepen their hold in the flesh of the fish with con- 

 vulsive grips. Suddenly a particularly violent contraction of the 

 female's body and limbs ejects the eggs from a single loop of the 

 oviduct. As a result of this, the very powerful claws, especially those 

 on the second antenna by which the animal maintains its hold on the 



Fig. I.— Egg string of Caligus rapax M. Edwards shed in captivity. The 

 Caligus is attached to a cod placed in an aquarium. It can be seen that the eggs 

 are not fully drawn out but are more irregularly arranged and therefore the 

 cement is not shaping separate cases around each single egg. 



host, are driven like spurs into the flesh of the fish. The fish feels 

 this as a strong irritation and leaps forward in the water. Since the 

 Caligus during this process is always fastened with its head pointing 

 forward toward the head of the fish, this leap of the fish and the 

 resulting resistance of the water will act as a backward-directed pull 

 or drag on the newly laid tgg masses covered by the freshly secreted 

 and yet unhardened cement. The eggs are thus pulled out into a long 

 string, like a string of pearls, before the secretion hardens. Further- 

 more, the pull is strong enough to separate the eggs slightly, which 

 not only leaves space for a membranous cement partition between 

 each egg, but also leaves a little empty space around the eggs. The 

 membrane divides the egg string into a series of narrow compart- 

 ments in each of which is a single egg which does not quite fill the 



