I'd expect an ampullarid to be larger.  There are numerous
morphological forms in the Lymnaeidae, treated as species by some
recent Russian workers (several papers by Kruglov and Starobogatov,
summarized in the 1993a and b papers in Ruthenica and more extensively
covered in Kruglov 2005).  You may find a match among the species
placed in Radix (which they treat as a subgenus and split into
numerous sections).  Anatomical features have some prominence, and
most other people think that they have oversplit the species; on the
other hand, treatments such as Hubendick (1951) overlump.

Kruglov, N. D. 2005. Molluscs of Family Lymnaeidae (Gastropoda
Pulmonata) in Europe and Northern Asia. Smolensk, SGPU Publishing. 507
p. [in Russian]
Kruglov, N. D. and Ya. I. Starobogatov. 1993a. Guide to Recent
molluscs of northern Eurasia 3. Annotated and illustrated catalogue of
species of the family Lymnaeidae (Gastropoda Pulmonata Lymnaeiformes)
of Palearctic and adjacent river drainage areas. Part 1. Ruthenica,
3(1):65-92. [in English]
Kruglov, N. D. and Ya. I. Starobogatov. 1993b. Guide to Recent
molluscs of northern Eurasia 3. Annotated and illustrated catalogue of
species of the family Lymnaeidae (Gastropoda Pulmonata Lymnaeiformes)
of Palearctic and adjacent river drainage areas. Part 2. Ruthenica,
3(2):161-180.  [in English]


--
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"

----------------------------------------------------------------------
[log in to unmask] - a forum for informal discussions on molluscs
To leave this list, click on the following web link:
http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1
Type your email address and name in the appropriate box and
click leave the list.
----------------------------------------------------------------------