SYSTEMATIC AND BIOLOGICAL ACCOUNT 81 



sac-like structure. Some of the better preserved eudoxids of Rosacea plicata from 'Discovery II' 

 Station 1617 show a homologous central organ and central organ complex. The central organ in 

 R. plicata is globular and is filled with a substance that may be of importance in controlling the density 



Text-fig. 36. Eudoxid of Nectopyramis thetis, from 'Scotia' 1951 St. 363. A, foreshortened dorsal view; 



B, lateral view; C, ventral view, x 5-5. 



.Angop 



■C/at. 



-C.rad v 



~Eud.Br. 



Angd 



Cd.-I. 



-CA/r 



■CM 



s mm 



Text-fig. 37. Nectopyramis thetis. A, dorso-lateral (antero-lateral sensu Bigelow, postero-lateral se?isu Leloup) view of eudoxid 

 from 'Discovery' St. 89, to show central organ and canals. B, dorso-lateral view of polygastric stage, x 6-6. 



of the eudoxid. The post-larva of R. plicata is provided with a similar organ. In that species, as the 

 nectophore grows, this part of the pallial canal decreases in size, and becomes the pedicular canal of the 

 muscular lamella attaching the nectophore to the stem. A similar somatocyst-organ can be seen in my 

 figure (Text-fig. 38) of the nectophore of Nectopyramis natans, and in Moser's (1924a) figure of the 

 larva of Rosacea cymbiformi;. 



