PLATE 38, 39, 40, 41. 
Volutions only two; the lower one, disproportionably large; 
the upper one, very minute and lateral, or placed on one 
side. 
Not common. The specimens figured, from Bakewdl. 
Fig. 3. Limestone. The smaller volution in this speci- 
men broken. 
4. A smaller specimen in Spar. Volutions perfect. 
This shell appears nearly allied to the Helix Haliotoidea, 
and some other species of a like form ; ditfering from the 
true Haliotides, principally in the want of the perforations 
which distinguish that genus. 
mining whether a fossil univalve, possessing no generic distinction in its 
form, be one which Linne would or would not have classed as an Helix- It 
will be here, perhaps, observed, that as the order of Testaceu consists wholly 
of genera, founded on artificial characters, taken from parts often wanting 
in fossil shells, the difficulty of ascertaining the genus of the originals, must 
frequently occur, even when the species petrified are evidently not Helices. 
To this we may answer, that in the Linnean arrangement of shells, the genera 
are mostly natural, though artificially distinguished— kni that, as in all 
truly natural genera, the wliole external appearance or habit is, for the most 
part, sufficiently indicative of the kind of body examined ; no great diffi- 
culty will be found to attend tfie determination of the original genera in 
fossil shells (except in the instance already noticed) although the teeth and 
mouth, the parts on which Linne has established his arragement of the recent 
subjects, are seldom visible in the petrified state. 
