214 Bulletin American Museum of Natural History [Vol. LIIT 
Alocinma is said to be provided around the margin with concentric 
lines. The penial structure also agrees with that of Bulimus tentaculatus. 
It appears therefore to be a bulimid snail, with the operculum less evolved 
than the type species of Digyrcidum, but of the same nature. It has 
the most primitive operculum of the bulimid series, as B. tentaculatus 
has the most evolved. It is therefore to be ranked as a subgenus of 
Bulimus, or as a very closely related genus. | 
BULIMUS Scopoli 
Bulimus Scopvo.t, 1777, ‘Introductio ad Historiam Naturalem,’ p. 392. For 
Helix putris, fragilis, stagnalis, and tentaculata of Linnzeus. Type by present designa- 
tion: Helix tentaculata Linneus. 
Bithynia Luacu, 1818, in Abel, ‘Narrative of a Journey in the Interior of China,’ 
p. 362. Type by original designation: Helix tentaculata Linnzeus. 
Bithinia Gray, 1824, Philos. Mag. and Journ., LXIII, p. 277. Monotype: Helix 
tentaculata Linneus. The generic name Bithinia was first published in 1821, London 
Medical Repository, XV, p. 239; but the only species cited there, P. ventricosa, he 
out description, was at that time a manuscript name. 
Bythinia W. MacGitutvray, 1848, ‘Hist. Moll. Aberdeen,’ p. 51. Monotype: 
- Helix tentaculata Linneeus. . 
Elona Moqutn-Tanpon, 1855, ‘Moll. France,’ II, pp. 516 and 527. Type by 
present designation: Helix tentaculata Linneeus. 
Shell imperforate, ovate-conic, thin, glossy; aperture ovate, slightly oblique, 
not contracted, the lip not thickened, sharp, the columellar margin narrow and ridge- 
like. Operculum solid, lodged at the edge of the peristome, calcareous within; the 
outer layer thin, cuticular, concentrically striate; the nucleus spiral, a little below and 
to the left of the middle. 
The animal has a well-developed right cervical lobe and the ae organ, in the 
type species, is conspicuously bifid. Radula having a broad central tooth with weakly 
trilobed basal margin and numerous basal denticles. 
» The genus Bulimus of Scopoli was proposed for four species which 
had previously been included in Helix, and one of these must necessarily 
be selected as the type, barring all surmises as to what Scopoli’s unex- 
expressed intentions might have been at the time. Of the four species 
cited, putris was subsequently placed in Succinea, fragilis and stagnalis 
in Lymnea, and tentaculata in Bithynia. The name Bulimus was after- 
wards improperly used for an extensive series of land shells. While it 
was clearly derived from the pre-Linnean Bulinus of Adanson (1757, 
‘Hist. Nat. Sénégal, Hist. des Coquillages,’ p. 5), the term had not 
before been used in Linnean nomenclature and cannot properly be re- 
stricted to the Adansonian species, which was specifically nameless at 
the time Bulimus was proposed. Moreover, it is a matter of conjeeture 
whether Scopoli’s change of spelling was due to an oversight or an inten- 
