Euphausiidæ. 



I. 



On the spawning of Euphausiidæ. 



This phase in the natural history of the Euphausiidæ 

 is still involved in much darkness, and it is highly desirable 

 that renewed investigations should be instituted about this 

 point. Whereas in other podophthalmous Crustacea, as is 

 well known, the ova are invariably carried by the female 

 during their whole embyronal development, either enclosed 

 in a marsupial pouch beneath the mesosome (Lophogastridæ, 

 Mysidæ), or more frequently attached to the ventral appendages 

 of the metasome (pleopoda), it is very rarely that ovigerous 

 Euphausiidæ are met with. Some observations, however, 

 prove that in fact Euphausiidæ too may carry their ova 

 for some time at least attached to their bodies. Thus, Th. 

 Bell found in a specimen of Nyctiplianes Couclii two sacs 

 filled with ova hanging down from the posterior part of the 

 mesosome, and I have myself, on going through the vast 

 material of Euphausiidæ collected during the Challenger 

 Expedition, recorded the occurrence of similar ovisacs in 3 

 different Euphausiidæ, viz., Nyctiphanes australis, Nema- 

 toscelis microps and Stylocheiron carinatum. It is, however, 

 very probable, that these cases are quite exceptional, and 



