304 
DEVONIAN FAUNA. 
a flattish base. Moutli, umbilicus, and surface unknown. Sinus-band apparently 
very narrow, and rather elevated. 
Size. — Height, 6 mm. ; width, 11 mm. 
Locality. — There is a specimen apparently from Lummaton in the Torquay 
Museum. 
Remarks. — I have been unable to find the type specimen of PI. gracilis^ but 
after careful consideration Mr. Roberts and myself came to the conclusion that 
the fossil described above must belong to that species. Phillips' figure of it 
represents a still flatter shell, with much broader whorls, but these differences 
may be due to the imperfection of the specimens. Thus, while the figure here 
given accurately represents one view of the Torquay specimen, its whorls seem, 
when viewed from another side, to be much more horizontally flattened, so that it 
much more nearly approaches Phillips' figure. 
The specimen is very poor, its surface is lost, and it is impossible to say 
whether the body- whorl is not partly absent ; but the size and shape of the sinus- 
band is clearly shown, and appears to be elevated, rounded, very narrow, and 
situate on the shoulder or widest part of the whorls. Phillips, on the other hand, 
writes of his fossil as if its sinus-band were depressed instead of elevated, but it is 
very difficult to be sure of his meaning. 
It seems very probable that it is also identical with Miinster's Euomphalus 
suhcarinatus^ which only differs in having a rather more elevated band or keel, 
and rather more numerous and slowly increasing whorls, so that the spire is 
larger. As the umbilicus of our fossil is unseen, I do not feel sufficiently sure of 
its identity to adopt Miinster's name, though I expect that it will ultimately 
prove that both the North and the South Devon shells will have to be referred to 
that species. 
Affinities. — Pleurotomaria sigaretus, Sandberger,^ is similar in general shape, 
but differs in its greater flatness, in the position of the sinus-band (which is not 
seen in Sandberger's figure), and in the section of the whorls being bluntly tri- 
angular instead of semi-elliptic. 
Natica discus, F. A. Romer,^ is also almost exactly similar, and in the figure 
there are some signs of an (unmentioned) band as in our specimen. It is difficult 
to decide upon such slight evidence whether it is the same shell. Romer mentions 
some backward lines of growth which might point to its being a Pleurotomaria. 
Clarke,* however, describes it under the name Turhinilopsis discus, F. A. Romer 
sp., and says that it is covered by microscopic spiral strige. 
1 1840, Miinster, ' Beitr.,' pt. iii, p. 85, pi. xv, fig. 15. 
2 1853, Sandberger, ' Verst. Rheiu. Nassau,' p. 194, pi. xxiii, figs. 9, 9 a, 9 6. 
s 1852, F. A. Eomer, ' Beitr.,' pt. 2, p. 88, pi. xiii, figs. 11 a, h. 
4 1884, Clarke, ' Neues Jalirb. f. Min.,' BeU.-Band iii, p. 351. 
