THE NAUTILUS. 



by Ancylus cumingianus Bgt,, which are generically distinct 

 from the European group of fluviatilis, will have to be known 

 by another name. 



As the establishment of the proper type of Ancylastrum. 

 thus becomes of very considerable importance in the classifi- 

 cation of the Ancylidcc, and as I have not been able to agree 

 with the position taken by the authors of this paper, it seems 

 proper to state the reasons that have influenced my decision 

 of the question before their suggestion has been generally 

 accepted. 



STATEMENT OF FACTS. 



Ancylastrum was first proposed by Bourguigiiat in the 

 Journal de Conchyliologie, IV, p. 63. This number of the 

 Journal is dated February 15, 1853. His paper is entitled 

 ' ' Notice sur le genre Ancylus, suivie d 'un catalogue synonym- 

 ique des especes de ce genre." Only the preliminary part, 

 the "Notice", was published at this time. On p. 63 the 

 author defines his new "S. G. Ancylastrum," but neither 

 names a type nor lists any species that he would include in it. 



In the next number of the Journal, issued May 1, 1853, in 

 a paper, which is entitled "Catalogue des especes du genre 

 Ancylus, 2e Article," Bourguignat published a complete 

 catalogue of all of the species of the genus then known to 

 him. Under the caption "ANCYLASTRUM" (p. 170) the first 

 species mentioned is Ancylus cumingianus Bgt., which he 

 states "is the type of the section Ancylastrum," and remarks 

 that "Cette magnifique espece, remarkable par 1 'excessive 

 deviation de son sommet, contourne sur lui-meme, habite la 

 terre de Van Diemen, dans la Nouvelle Hollaude." He fur- 

 ther states that he regrets that he is unable to give the diag- 

 nosis of this and certain other new species from the Cum- 

 ingian collection for the reason that he had promised Mr. 

 Cuming that they should appear first in the Proceedings of 

 the Zoological Society of London. He then proceeds with his 

 catalogue, which shows that he included all of the known 

 Ancyli in Ancylastrum except those having the apex directed 

 to the left side. 



