390 GASTEROPODA OF THE INFERIOR OOLITE. 



On the other hand, there occurs in the Goncavus-hed at Bradford Abbas a 

 remarkable trochoid species, which, although it is probably not a Trochus, I may 

 enumerate provisionally under this genus. 



332. " Teochus" attroohus, sp. nov. Plate XXIX, fig. 15, and var. fig. 16. 



Description : 



Height ..... 5*5 mm. 

 Width . . . . .6 mm. 



Shell irregularly conical, thin, subumbilicate. The angle of the spire is regular, 

 but owing to the sudden increase of the body -whorl, the spiral angle of the entire 

 shell is concave. In fact, so ventricose is the body- whorl that, in some cases, the 

 spire has the appearance of belonging to another shell. Total number of whorls 

 five; those of the spire are flat (smooth at the extreme apex), whilst the penult 

 and antepenult are ornamented with a loosely granulated spiral on the posterior 

 margin, and a finely granulated keel anteriorly. 



The body-whorl is angular and enormously ventricose, and separated from the 

 spire by a wide and subcanaliculate suture. The ornaments are the same as in the 

 lower whorls of the spire, viz. a circlet of distant nodules on the posterior edge, 

 and a conspicuous carina with fine granulations ; this carina is median, and above 

 it there are no certain traces of spiral lines, whilst below and in the base are 

 considerable indications of spiral lines. Base widely but not deeply excavated. 

 The aperture is large and prominent anteriorly, the lips being somewhat thin, 

 outer lip angular, inner lip circular. N.B. — The thickening of the inner lip, 

 shown in Fig. 15, is not quite correct. 



Varieties. — There is considerable irregularity of development. In some 

 specimens the whorls of the spire appear undercut owing to the salience of the 

 the carina ; in these cases the body- whorl is usually less ventricose, and the shell 

 more regularly conical. The variety from Beaminster (fig. 16), besides being 

 smaller, shows some modification in the spiral ornament below the carina of the 

 body-whorl, and otherwise differs in some minor points. 



Relations and Distribution. — At present this curious species seem to stand 

 alone with reference to the other Gasteropoda of the Inferior Oolite. It may be 

 related to some of the perforated Trochi of the Paleontologie Francaise; but 

 Gemmellaro's genus Palgeoniso, if one may judge from the species described and 

 figured by that author, does not seem applicable in the present instance. 



Known only from the Concavus-bed at Bradford Abbas and the parallel horizon 

 at Beaminster. 



