426 GASTEROPODA OF THE INFERIOR OOLITE. 
The sinus-band is situated a little above the centre of the subcarinal portion of 
the whorls ; it is wide, flat, and non-salient; a strong spiral line in the middle may 
be noted, but later on this seems to undergo modification. The body-whorl is 
bicarinate with a sharp angle at the periphery (more like d’Orbigny’s figure than his 
description). Generally, too, the basal angle is subnodular, almost like that in PI. 
subfasciata. Base flat, with a large umbilical excavation, the spiral striz being 
faint and confined to the outer margin. Aperture oval and oblique. 
Relations and Distribution—As a member of the Proteus-group its relations 
have already been partially indicated. The figured specimen is from the Iron-shot 
Oolite of Dundry. TI have a large specimen from the Humphriesianus-zone of the 
Sherborne district, and a few smaller ones. It is less abundant than the species 
next described. 
367. Prevrotomaria Proreus, Deslongchamps, 1848. Plate XXXVII, fig. 2. 
1848. Prevroromaria Prorevs, var pxcrtsa, Deslongehamps. Vol. cit., p. 50, 
pl. i, fig. 1. 
1854. -- --- Deslongchamps. D’Orbigny, Terr. Jur., vol. ii, 
p. 453, pl. ecelxx. 
1873. 
— Tawney, Dundry Gasteropoda, 
p. 52 (44). 
N.B.—It should be borne in mind that specimens, such as the one figured, are 
incomplete, and do not attain to the smooth stage, as is the case with the very much 
larger ones in Normandy. 
The height of the largest British specimen known to me is about 50 mm. ; 
whilst the spiral angle is at least 10° narrower than in Pl. paucistriata ; the whorls 
are drawn out axially and have a rather different shape, whilst the umbilicus is 
very narrow. ‘The nodules on the carine are bolder and more wide apart in PI. 
Proteus than in Pl paucistriata, but there are intermediate forms. The elongate 
specimens which I refer to Pl. Proteus are most abundant in the Humphriesianus- 
zone of Louse Hill; and, generally speaking, the group is chiefly found in the 
Sherborne district. 
From Louse Hill (upper part of Humphriesianus-zone) I have likewise a portion 
of a large specimen indicative of Pl. constricta, Deslongch. This species, as the 
author remarks (vol. cit., p. 42), links the varieties of Pl. Proteus with those of Pl. 
armata. 
