STRAPAROLLUS. 319 
Shell depressed, discoidal ; under surface largely excavated, upper surface flat 
or scarcely concave. The whorls are numerous, narrow, quadrangular, with 
flattened sides, which in some specimens exhibit more tendency towards contrac- 
tion anteriorly than in others. The marginal keels are closely tuberculated, the 
tubercles being rather round and small. These tuberculations are of equal 
strength on both upper and under surface, but are scarcely connected by cost 
across the flanks of the body-whorl. The entire shell is richly ornamented by a 
trellis-work of spiral lines decussating with growth-lines. Aperture quadrangular, 
the axial diameter considerably longer than the spiral. 
Relations and Distribution.—This beautiful species is easily distinguished from 
those previously described by the narrowness of the whorls and the peculiar 
roundness and closeness of the nodes. In the character of the spiral lines it 
somewhat approaches Discohelix Cotswoldiz, but differs greatly both in orna- 
mentation and the shape of the whorls. ‘To a certain extent our shell resembles 
Str. pulchellus, @Orb. (¢T. J.,’ ti, p. 312, pl. ccexxiii, figs. 1—4), but that species 
is more depressed, and its whorls are triangular rather than square. 
Straparollus pulchrior is essentially a fossil of the Murchisone-zone. I have 
specimens from Mapperton, Coker, and Bradford Abbas, at all which places it is 
very rare. Apparently it occurs also at Dundry. 
252. Srraparottus Dunpriensis, Tawney, 1873. Plate XXVI, fig. 2. 
1873. Srraparotitus Dunpriensis, Tawney. Dundry Gasteropoda, p. 35 (27), 
pl. ui, figs. 9 a, 9b. 
Description : 
Diameter . 5 : 2 . 18 mm. 
Height : ‘ ; : a opm 
Shell depressed, discoidal; under surface considerably excavated, upper 
surface nearly flat, or sometimes slightly raised. The whorls are numerous, 
quadrangular, narrow (spirally), deep (axially); the sides are flattened with a 
considerable amount of anterior contraction as shown in the body-whorl. The 
tuberculations on the upper marginal keel are very dense and round, and the 
effect is to raise the keel considerably, and thus produce a sulcation of the 
rest of the upper surface, which also has about four dotted spiral lines between 
the rows of tubercles. 
The body-whorl is deep, its height being equal to half the total diameter 
of the shell, though there is some difference in this respect; ornamented on 
the flank with spiral lines, which decussate with curved growth-lines so as to 
produce a rich reticulate pattern. The upper angle is somewhat less than a right 
