310 



OpHILETA ? BELLA. (N. Sp.) 



0. uniangulata. Geol. Can., p. 860 ; aiite, p. 246. 



Fig. 301. 

 Fig. 301. — Ophileta bclla. Dififerent views of a nearly perfect specimen. 



Description. — From one to two inches across ; lower side flat or gently 

 concave ; upper side concave, with a strongly elevated narrow^ spiral band ; 

 whorls, four or five. On the lower side, the whorls are usually moderately 

 convex, but sometimes they are flattened on the inner half. The outer 

 side of the whorls are convex. On the upper side, the spiral band some- 

 times runs along the middle of the whorl, as in fig. 301, c, but its position 

 varies between the middle and the outer edge. The aperture has an 

 angular notch above with the apex at the termination of the band : on the 

 lower side, a flexure backwards. Surface Avith coarse, sub-squamose, 

 transverse lines, of growth about six in two lines. 



The whorls are often somewhat larger in proportion to the width than in 

 the specimen above figured. 



I have heretofore referred specimens belonging to this species to the 

 Uuomjyhalus imiangulatus (Hall), but the recent discovery of a number of 

 good specimens leads me to regard it as a distinct, although a closely allied 

 form. That species has the lower side deeply concave, forming a deep 

 umbilicus like Helicotoma planulata (Salter) ; while in this, it is usually 

 flat, and when concave, is only moderately so. The whorls in this species 

 are also more compactly inrollcd. 



I have stated {ante, p. 236,) that the genus Opldlcta was founded on 

 species of Maclurea, with very slender whorls. The specimen above 

 figured was discovered since that page was printed. It shows very clearly 

 that the aperture has a sinus in the lower lip, and a notch in the upper, 

 characters which are not at all exhibited by perfect specimens of Maclurea 

 Logani. In M. crenulata {ante, p. 236,) there is a sort of spiral band, 

 and, also, there are indications of a sinus in the lip on the flat side, but 



