PLBUROTOMARIA. 
301 
in the other; moreover the direction of the oblique lines is very different, and one 
or two other distinctive features exist which prevent its union with it, which^ 
chiefly from the paucity of the material, I was at one time inclined to propose. 
Affinities. — ScJiizostoma costatum, Goldfuss,^ is sinistral, and its ridges seem 
fewer and less oblique than those of the present species. Its sinus-band also 
appears much narrower, like that of the genus Porcellia. 
Worthenia Munsteriana, de Koninck,^ has a larger and more elevated spire. 
PI. Larteti, (Ehlert,^ is very similar, but is a more conical shell with more 
numerous whorls and a less inflated body-whorl. 
16. Pleurotomaria viotrix, Whidhorne. PI. XXVIII, figs. 15, 16. 
? 1841. Pleubotomabia aspeea, Phillips (pars), not Sowerhy. Pal. Poss., p. 223, 
pi. xxxvii, fig. 177* only. 
1854. — — Morris, Catal. Brit. Foss., p. 272. 
1889. — viCTEix, Whidhorne, Geol. Mag., dec. 3, vol. vi, p. 30. 
Description. — Shell large, turbinate, rather elevated, angulated, of about four 
volutions. Spire increasing rather slowly, somewhat elevated. Suture simple, 
deep, rather broad. Whorls broad, sub-circular, much exposed, moderately convex 
above, the curvature increasing at the lowest and widest part, where there is a 
rapid rounding-in to form a spirally convex base. Sinus-band narrow, elevated, 
flat or slightly concave, bounded by a minute groove and edge, which become a 
ridge on the upper whorls ; situated about the middle of the body- whorl, or in the 
upper whorls about twice its width above the suture. Ornament consisting of 
three fine equally distant threads above the sinus-band, and numerous close 
minute spiral threads on the base of the shell, the whole crossed by microscopic 
characteristic growth-strise which are unusually steep on the upper part of the 
whorls, and become coarser on the base so as to break the spiral threads. 
Size. — Height about 27 mm. ; width, 23 mm. 
Localities. — There are two specimens in my collection from Lummaton, another 
fragment (probably of the same species) from Lummaton in the Bristol Museum, 
and a very poor specimen from Wolborough in the Grodwin-Austen Collection in 
the Museum of Practical Geology. 
Remarks. — Upon the upper whorls the spiral threads are so strong as to give 
a polygonal shape to its section, but upon the body-whorl they become very 
indistinct. This species comes near to PI. delphinuloides in some respects, but it 
is more angulated than any of the varieties of that species, and also has a narrower 
1 1844, G-oldfuss, ' Petref. G-erm.,' vol. iii, p. 79, pi. clxxxviii, figs. 7 a, b. 
2 1883, de Koninck, ' Ann. Mus. Eoy. H. N. Belg.,' vol. viii, pt. 4, p. 66, pi. xxxii bis, figs. 7, 8. 
3 1887, (Ehlert, 'Bull. Soc. d'Etude Sci. d' Angers,' p. 25, pi. xxix, figs. 1, 1 a—e. 
