68 



HYDROIDA II 



the apophyses, which is here evident at the first glance. In this case, it would scarcely be possible 

 for anyone to doubt that the specimen is a young Nemertesia, the more so since the stem is strikingly 

 thick. Further confirmation is in both instances afforded by the branch apophyses [c and e)\ in both 

 colonies we find the characteristic "mamelon" on the upper side of the apophyse, close to the stem, 

 which proves that they belong to the Nemertesia. The entire arrangement of the hydrothecae and 

 sarcothecse also shows that the species is Nemertesia ramosa. 



The stages found already show that the younger Nemertesia are throughout constructed after 

 the Plumularia type, with biserial apophyses, and that Nemertesia must be derived from Plumularia. 

 It would further seem to suggest that Plumularia caulitheca Fewkes is probably a young stage of a 



2 00 m. 6oom. looom. 2ooom. 



Fig. XXXIII. Occurence of Nemertesia ramosa in the Northern Atlantic. 

 In the hatched region the literature notes a common occurrence. 



Nemertesia. And it is likely that also other Plumularia species in reality cover young Nemertesia 

 species, and should, from the presence of a "mamelon", be transferred to that genus. 



Among the synonyms of Nemertesia ramosa should also be reckoned Antennularia variabilis 

 Broch. The defective srjecimens, where only the chitinous parts are preserved, have lost all their 

 sarcothecse, so that only a hole in the periderm, or a slightly raised part here and there, shows where 

 the sarcothecse have been. The difficulty of discerning these remains has led to their being regarded 

 as variable in number, and the remains or traces of supracalycine sarcothecse had altogether escaped 

 attention. Otherwise the colonies agree entirely with Nemertesia ramosa, and must thus be referred 

 to that species. 



Nemertesia ramosa has its chief occurrence in the littoral region, especially in the middle and 



