THE - CONCHOLOGISTS’ - EXCHANGE. 
1¥3 
LYOGYRUS, GILL, AND OTHER 
AMERICAN SHELLS 
BY H. A, PILSBRY, PHILA., PA. 
The genus Lyogyrus was established in 
1862 for the single species Valvata pupoidea 
Gld. Its distinctive characters as stated by 
Mr. Gill, are found in the elongated form and | 
last whorl loose from the preceding. From this 
last character the shell receives its name, Zyo 
(zo) meaning loose in the Greek, 
this in order to correct a false etymology, Zzo- 
gyrus, that-has found its way into print. 
This group has been referred to Valvatide 
as a subgenus of Va/vata by Binney, Tryon, 
Fischer and others who have treated of it. 
Upon examining specimens in the Academy col- 
lection recently, I ascertained the dentition to | 
be Amnicoloid. The operculum is multispiral, 
and similar to that of Va/vata, These peculi- 
arities are sufficient to give generic rank to the 
group, which may be placed next to 4m- 
nicola in the system. ‘Tryonin 1883, and Fis- 
cher in 1885, referred /e¢erocyclus, Crosse, to 
this genus. Itis hardly worth while to specu- 
late upon this point until the dentition of the 
new Caledonian form is examined, 
A single species, 2. pupoides, Gld., is known. 
The form recently described as Z. Lehnerti 
has no affinity with the present genus, but is 
simply a monstrosity of Amzzcola, possessing 
paucispiral operculum and other characters of 
that genus. Such distorted shels are of not 
infrequent occurrence, and their characters 
having no constancy, of ever varietal rank can 
be given them. 
Although American Conchologists have not 
been finding “new species” of fresh water 
shells in the Eastern States for the last decade 
or two, Continental writers, with delicious cool- 
ness, continue to describe ‘‘ novelties” from 
Massachusetts, Maryland, and other well- 
known localities. 
In regard to another late edition to the nom- 
enclature of U.S. shells, we may note that in 
place of Zrtodopsis Harfordiana, W.G, Bin- 
ney (preoc in //e/zx), Mr. Tryon, in Sept. 
1887. proposed the name of /. Sa/monensis. 
This will of course take precedence over the 
name 7. commutanda, Ancey, 1888. 
I mention | 
| and specific names recently proposed. 
| 
Another of these ‘‘new species ” is the Va/- 
vata mergella, \Vesterlund, described last year 
from Alaska. This is nothing more than the 
striate variety of V. stzcera, Say. The species 
frequently in the north exhibits strong rib-like 
strize; and indeed the names I. s¢r?atew, Lewis, 
and V. Lezwz7st Currier, were applied to this very 
form, 
The fact that the nomenclature of our 
American shells is becoming so over-burdened 
with synonyms will perhaps justify me in offer- 
ing a few additional remarks on useless generic 
In an article in Ze Waturaliste, in which 
certain of Mr, H. Crosse’s genera are rudely 
| handled, Mr, C. F. Ancey, proposes for the 
| Physa (“ Paludina”’) scalaris, Jay, the subgen- 
eric name of “ 7hompsonia.” And, scalaris 
being preoccupied in Physa, changes the name 
of the species also, so as to stand /hysa@ 
( Thompsonia) carinifera, Ancey. We will now 
analyze this result. That this Floridan species 
is not a Physa was long ago recognized by one 
of the foremost of American Conchologists, 
who, in an admirable revision of the Limnue- 
zde, placed it in the exotic group Ameria. 
From a study of alcoholic material and very 
numerous specimens of the shells, I find that 
the real position of the species is in P/anorbzs, 
and that some of its varieties are exceedingly 
close to the Planorbis Duryt, Wetherby. We 
may consider sca/arvzs to be a lengthened form 
of the section of Planoréis known as fYelisoma, 
So much for the generic reference. In view of 
these indisputable facts, Zompsonta becomes 
asynonym of /e/isoma. But even if it were 
distinct, we could not use the name, because it 
has long been in use in Zoélogy for a univers- 
ally accepted genus. And since, so far as I 
can ascertain, sca/aris is not preoccupied in 
Planorbis, that name may still stand for the 
species, with carzzzfera as a synonym. 
Academy of Natural Sciences, Feb., 1888. 
Prof. Cattell, of the University of Penna., 
read a paper recently before the Aristotelian 
Society, at London, on ‘ The Psychological 
Laboratory at Leipzig.”” The paper appeared 
in January AZ. 
