26 Tuhicolous Marine Worms. 



in diameter more rapidly, so that there is a deep and narrow 

 umbilical cavity in the centre. It is found both on stones and 

 sea weeds in deep water. This is at least what I take to be the 

 true Seiyula spirorUs of Linnae us and Fabricius, though more 

 recently some confusion between this shell and S, spirillum seems 

 to have arisen. It was found by Fabricius in Greenland. I have it 

 in a collection made in Labrador by Mr. Carpenter, missionary 

 of the Canada Foreign Missionary Society, and Dr. Gould has ob- 

 tained it on the American coast. I have it also on stones from 

 the Banks of Newfoundland. 



When old, this shell forms a few semi-erect turns, so as to cover 

 up the previous whorls and the umbilicus, and terminates in a 

 thick and slightly expanded mouth, sometimes as much as half a 

 line in width. So completely does the shell in this condition 

 differ from its immature state, that but for the appearances seen 

 in sliced or broken specimens, I should have regarded it as a 

 distinct species. A change of a somewhat similar character, 

 though less marked, occurs in S. cancellata, and is represented 

 in the figure of that species given below. Similar changes, 

 though with diflferences in details, occur in S. vitrea and S, 

 por recta. 



Spirorhis carinata (Mont.) is a deep water species, closely allied 

 to >S^. nautiloides, if not a variety of it. It is distinguished by 

 a keel or ridge running along the whorls, nearer the inner than 

 the outer edge. In some old shells a second ridge appears, and 

 then the shell very closely resembles S. quadrangularis of Stimp- 

 son. Young shells, on the other hand, are not distinguishable from 

 those of the S. nautiloides. This species is not noted by Fabricius 

 as a Greenland shell. It abounds in the collections of Mr. Bell 

 of the Geological Survey, and in my own from Gaspe, where it 

 occurred in deep water, attached to dead shells and stones. It 

 was found at Labrador by Mr. Carpenter. I also have it on a 

 stone taken up from the Banks of Newfoundland by a fishei man's 

 hook, and presented to me by A. Dickson, Esq. 



Sp>irorhis vitrea is like S. sinistrorsa^ a reversed species, but is 

 thick, semi-transparent, and has the whorls closely crowded, and 

 in adult shells turned up and somewhat narrowed and thickened 

 at the mouth. A group of these shells looks like a number of 

 small drops of glass that had fallen on a stone and cooled there. 

 Fabricius discovered this species in Greenland. It occurs in Mr. 

 Bell's Gaspd collection, on the Banks of Newfoundland, and fossil 



