MEDUSA. I. 



13 



Though the species has, mainly, a bathypelagical occurrence, it may, however, occasionally rise 

 to the upper water layers. On "Michael Sars" stat. 81 a specimen was fished by the ringtrawl with 

 100 m wire in water of a fairly high temperature (about 13° C). 



More astonishing is the find, made by M oiler, off the west coast of Greenland (see above, 

 p. 9). It is a well-known fact that oceanic deep-sea organisms are occasionally carried towards the 

 west coast of Norway and found there near the shore and in the upper water layers. vSimilar pheno- 



Chart I. Occurrence of CItromatonema riibritm Fewkes in the northern .\tlantic. 



mena have been observed on the west coast of Greenland, and this may account for the appearance 

 of this oceanic deep-sea medusa comparatively near the coast and swimming at the surface of the water. 



The hydroid stage is imknown, and no young stage of the medusa has been observed; it is 

 impossible, therefore, to state, or even to guess, anything with regard to the development of the species. 



Related vSpecies. — Bigelow (1909) has described a similar medusa from the eastern tropi- 

 cal Pacific (the Humbolt-Current off the coast of Peru, in intermediate strata). He called it Ptychogena 

 erythrogonoii. Bigelow possessed a series of specimens in different stages of growth, the largest being 

 38 mm in diameter by 25 mm high. The general appearance of the species bears a striking resem- 



