218 MAGILINA, NISEA. 



hence in other stages of growth, additional specific names have 

 been made. M. Robillardi, Lienard (figs. 422, 423), is one of 

 these less-developed stages. Coralliobia cancellata and sculptiliB 

 of Pease, neither of which have been figured, present no distinc- 

 tive characters in the descriptions, and may be here included. 



Genus MAGILINA, Velain. 



The species which forms the type of this new genus is much 

 smaller than those of Magilus. The distinctive characters con- 

 sist in the spiral shell having one whorl only and in the fixed 

 adult being attached by one side of the tube to the external 

 surface of submarine objects instead of growing in their interior. 

 This is a great change of habit, and the animal may prove to 

 have no relationships with Magilus but rather with the Vermetidae. 

 I do not know how closely it may be related to Nisea. 



M. SERPULIFORMIS, Velain. PL 69, figs. 425, 426. 



Shell at first' thin, transparent, deep red-brown ; growing into 

 an irregular tube affixed by its side to shells, etc., and then 

 becoming whitish. Length 3-4 mill., diam. 1*25 mill. 



Isles of St. Paul and Amsterdam, Indian Ocean. 



Animal and operculum unknown. 



Genus NISEA, Marcel de Serres. 



A fossil of very doubtful affinities, of which two species have 

 been described. 



N. SIMPLEX, M. de Serres. PI. 69, fig. 424. 



Lower Crag, vicinity of Ni 



