362 JOURNAL OF CONCHOI.OGY, VOL. ID, NO. 12, OCTOBER, I903. 



Acroloxus Beck,^ for "Aneylus lacustiis (L.) O. Miill." and other 

 species has precedence over Velletia Gray, 1 840. 



Limncea. — This name was used by Poll ("Test. Sicil."i., 1 7 1 1, Introd. 

 31) as a generic term for the animals of certain Uniones, Mytili, etc. 

 His habit, however, of giving one name to the animal and another to 

 the shell containing it has led to the total disregard of his work as 

 a serious contribution to zoological nomenclature. 



Limntsa pereger (Miill.). — The Helix limosa of Linnd is, as 

 Hanley says, "too imperfectly defined for positive determination" and 

 must be set aside. Miiller was unaware that pereger is a substantive 

 without an adjectival equivalent so that the specific name must remain 

 in the nominative in apposition, like Pecten lens, Ostrea fro7is, &c. As 

 for the variations in form, their name is legion but it is worthy of note 

 that one Z. ampla, of Hartmann, so closely resembles L. auricularia 

 as frequently to be mistaken for it. 



The Helix balthica Linn., was identified by Nilsson as a Limncea 

 which he found living in brackish water on the shores of the Baltic 

 which is the same locality as given by Linnd Hanley considers that 

 Nilsson's opinion is entitled to respect, but does not advocate its 

 adoption. It is, however, by no means certain that Nilsson's con- 

 jecture is correct, there are several forms that would equally suit Linnd's 

 vague diagnosis, while the statement "rugis elevatis" is distinctly 

 inapplicable to any Liamcea and nothing of the sort was observable on 

 any Limncea balthica in the collections in the Natural History Museum 

 and no specimen is in the Linnean collection. Nilsson's Liinncea 

 balthica has been identified as a form of Z. pereger and since for 

 reasons above stated it cannot be shown to be the same as Linnd's the 

 name if retained as a variety of Z. pereger \n the list must be attributed 

 to JVilsson, NOT to Linne. Could the identity of Nilsson's form with 

 Linnd's be established Z. balthica (Linn.) would have to replace Z. 

 pereger (Miill). 



It seems pretty clear that Z. involuta Harv. is a local race of Z. 

 pereger rather than of Amphipeplea glutinosa, and in this respect it 

 stands on the same footing as Z. burnetii Aid., so that the two should 

 be treated alike, either as varieties of L. pereger, or allowed to rank as 

 distinct forms. It has been the fashion to reckon the former as a 

 species and the latter as a variety, but as pointed out by Mr. Lionel 

 Adams^ the young shell of Z. burnetii has an involute spire while the 

 embryo shell of Z. involuta has not. These embryonal characters are 

 of great importance hence I would advocate the restoration of Z. 

 burnetii to specific rank. 



Stagnicola, proposed originally by Leach, in his unpublished 



I " Ind. Moll.," 1837, p. 124. 

 z /. Conch,, vol. 9, p. 299. 



