PLEUROTOMARIA. 
277 
His figure does not look at all like our specimens, but it is only a cast, and is 
evidently imperfect or distorted. Hence there is some difficulty in fixing upon the 
right name for our fossils. 
D'Orbigny points out that Brocchi ^ had already used the name Turbo sub- 
angulatus for a Tertiary fossil, and calls it T. niso ; but if Phillips's shell is the 
same as Sowerby's, his name would take precedence to D'Orbigny's. 
IX. Family. — Pleurotomariid^, UOrbigny, 1842. 
1. Genus. — Pleueotomaeia, Defrance, 1826. 
This large and well-known genus, starting in the Silurian, is found in almost 
every succeeding form to the present time. In the Palgeozoic and Mesozoic periods 
it abounded and is represented by many hundred species. In the Tertiaries it 
was rare and there are only four living species. 
Our Devonian species show much variability of shape, and belong to several of 
the different sections into which de Koninck and others have subdivided the genus. 
1. Pleueotomaeia Ohampeenowni, n. sp. PI. XXVI, figs. 1 — 5. 
1889. Teochtjs mtjltispiea? Whidlotne (not Sandler ger). Geol. Mag., dec. 3, 
vol. vi, p. 30. 
Descriptio7i. — Shell rather large, spiral, turrited, trochiform, of six or seven 
narrow and very slowly increasing volutions. Apex probably blunt. Spire 
conical or hive- shaped. Sutures very deep, acute, and vertical. Sutural angle 
very small and regular. Whorls very narrow ; in section subquadrate, horizontal 
above and below, with slightly convex and nearly perpendicular back. Sinus- 
band central, broad, elevated, and slightly concave, containing a fine thread-like 
central line, and having the flexions of the transverse lines in it shallow. Surface 
above the sinus-band bearing two or three round, low, massive, spiral ridges, 
separated by similar grooves. Surface below the sinus-band first forming a small 
groove, and then curving round the lower and widest part of the shell to form the 
broad, flat, smooth, and nearly horizontal base. Growth-lines and secondary spiral 
markings very fine and indeed microscopic. Mouth very wide, subquadrate. Inner 
lip straight, slightly thickened, vertically twisted or corkscrew-like, so that it is 
slightly excavate at the lower corner of the mouth. Umbilicus, if any, very minute. 
1 1814, Brocchi, ' Conchiologia Foss. Subapeunina,' vol. ii, p. 374, pi. vi, fig. 16. 
