142 GASTEROPODA OF THE INFERIOR OOLITE. 
ments consist of stout coste distributed at wide intervals in the form of varices, 
not usually in alignment, chiefly on the posterior area of each whorl, and very 
nodose in passing over the keels. Below the keels one, and sometimes two strong 
spiral bands may be noted, almost giving the appearance of bicarination ; the lesser 
spirals are fine and numerous throughout the shell. 
The Ponton variety presents the most interest, since here alone have I been 
able to find a specimen with the Ne developed (or preserved), fig. 8 b. 
Length : . 22 mm. 
Width of body-whorl to beiett 6 shell. . 45: 100. 
Spiral angle about... 380% 
Probable number of whorls seven or alte. Ornamentation of the spire-whorls 
as already described. Body-whorl tumid, sub-bicarinate, with two or three coarse 
nodular varices, and traces of numerous diverging spiral lines. Wing wide and 
short, and enveloping nearly half of the penult, apparently without digitation- 
Aperture wide and subquadrate, with an expanding lip, anterior margin slightly 
excavated ; columella curved and but slightly encrusted ; canal apparently almost 
as short as in Brachytrema. 
The Weldon variety, which is presumed to be an immature form, and which 
might almost be regarded as a distinct species, is most characteristically repre- 
sented by fig. 8’ a, a well-preserved specimen of the more usual form. See also 
Pl. II, figs. 10: a, 10 5. 
Length : : . 10O—12 mm. 
Width of body-whorl fe height of shell <= . 55: 100. 
Spiral angle about —. : ; . 40°. 
A wide-angled, stumpy little shell of about six whorls. Body-whorl tumid, 
sub-bicarinate, spirally striated, and carrying three or four varices. There is no 
wing. Aperture wide, with a simple lip, and very short anterior canal, almost 
like Brachytrema. 
A sub-variety of the Weldon fossil is shown in fig. 8’ b. 
Probable length : 5 : a mm 
Width of body whorl to height of shell ‘ ‘ = LOO: 
Spiral angle about : : : ae 
Probable number of whorls six or seven ; ornamentation apealen to the last upon 
a narrower and more turrited spire. Body-whorl keeled and spirally ornamented, 
but entirely without varices. Other indications wanting. This is rare. 
Relations and Distribution.—Accepting the adult specimen from Great Ponton 
(fig. 8 b), for the moment, as the type of the group, there is nothing like this known 
from the Inferior Oolite of the other districts. The form of the wing and the 
character of the aperture remind us of certain specimens of Alaria (Diartema) 
paradoxa, M. & L., a well-known fossil of the Great Oolite, but the spire is very 
