WOODWARD : LIST OF BRITISH NON-MARINK MOLLUSCA. 363 



" Synopsis," was not quoted in literature till Turton's " Manual " 

 appeared late in 1831 (Oct.) ; meantime the name had been proposed 

 earlier in that year (July) by Brehm for a genus of Aves. Since, 

 however, Limnma stagnalis is the type of the genus no further sec- 

 tional name is necessary. 



Omphiscola Rafinesque {/ourn. Fhys., vol. 88, 1819, p. 423) was 

 defined by him as :— " Different du Lymnule {Lyituiea Auct.) par 

 levre inferieure de'tachee de la columella, avec un ombilic oblong 

 entre elles." This can only refer to the L. pereger and L. auricularia 

 group (for which Montfort's Radix already stands), so that Beck's mis- 

 application of the name to Z. glabra cannot be accepted, and it is 

 necessary to take Swainson's Leptolimncea, founded for L. glabra in 

 1840. 



Planorbis Guettard being pre-Linnean the name must be attributed 

 to Geoffrey, the first post-Linnean writer to make use of it. 



Coretus Adanson is also pre-Linnean, and not apparently adopted 

 by any post-Linnean author before Gray in 1847. 



Gyrorbis Fitzinger, 1833, is a synonym for Valvata and not as has 

 been cited for Tropidiscus^ Planorbis \s.s^ Ag. 



Planorbis glaber ]e^x. — It has frequently been alleged of late years 

 that this species is identical with P. parvus Say. As pointed out by me 

 in 1890^ this is not correct, and Prof Dall, who obligingly examined 

 the types, which are in the U.S. National Museum at Washington, and 

 sent co-types over, now in the British Museum (Natural History), 

 supported this view, writing '■'■ Planorbis glaber Jeffreys, in my opinion, 

 is distinct from P. parvus. The latter is flatter and less deeply 

 umbilicated, and shows much more of the whorls within the outer one. 

 It is also distinctly less polished in the average specimen." In the 

 original description, too, it is said to be "generally subcarinate on the 

 margin." As a matter of fact both P. parvus and P. glaber would 

 appear to be racial off-shoots from the boreal P. arcticus Beck, and 

 must either be ranked as forms of one species, which in the apparent 

 absence of linking forms seems undesirable,^ or, as I think preferable, 

 retain their distinctive nomenclature as suggested in the parallel case 

 of Lifnncea pereger, L. burnetii and L. involuta. The dates of 

 foundation are: — 



P. parvus Say, Nicholson's Encyc.,Ed. 3 (i8i9),vol.4 "Conchology," 

 t.i.f., 5. 



P. glaber ]q^., Trans. Linn. Soc, 1830. 



P. arcticus Beck, "Ind. Moll," 1837. 



1 Proc. Geol. Assoc, vol. ii, p. 381. 



2 Mr. Johansen writes that though formerly of this opinion he now, after inspecting a great 

 number of examples, considers them one species. 



