SEA-FISHERIES LABORATORY. 



293 



never been taken with extruded eggs attached to the 

 genital segment, and it is therefore highly probable that 

 the fertilised ova are set free directly into the sea. We 

 have observed this pelagic egg from time to time for some 

 years, bnt as the embryo was too immature we were 

 unable to assign it to any animal. A few were taken in 

 the '09 collections which clearly show the Nauplius inside. 

 We add here a sentence published* more than twent}^ 

 years ago by our friend the late Mr. Isaac C. Thompson, 

 in regard to the ova of Calanus found in gatherings from 

 the North of Norway, which he was examining at that 



Fig. 9. Pelagic egg of Calanus, x23*5. 



time: — ". . . in some of the localities about the North 

 Cape . . . this species [Calanus finmarchicus , Gunner] 

 forms almost the entire mass in the tow-net. Its profusion 

 here enables us to clear up a most interesting question. It 

 has been often remarked that in this, as in some other 

 species of Copepoda, the precise manner of ovi-position is 

 mysterious inasmuch as females with ovisacs have never 

 been noticed, though carefully looked for .... It has 

 often struck me as probable that Calanus finmarchicus 

 casts its ova directly into the sea just as fishes do, and its 

 profusion in these northern localities has furnished the 

 opportunity of establishing what seems to be a clear proof 



* Trans. Liverpool Biol. Sqc, Vol. Ill, pp. 80.. 81, 1889. 



