330 DEVONIAN FAUNA. 
B. glohatus, Sowerby,^ differs in having an open umbilicus and a more flattened 
back. 
2. Genus — Porcellia, Leveille, 1835. 
Leveillia, E. B. Newton, 1891. 
This genus is marked by its grooved or fissured back, its long narrow notch, 
its very open umbilicus and correspondingly depressed spire, and by its unex- 
panded mouth. It occurs from the Upper Silurian to the Trias. 
The genus has long been well known under the name Porcellia, but my friend 
Mr. R. B. Newton, in a recently-published paper,^ stating that Leveille's name is 
essentially the same as Porcellio, a genus of Isopodous Crustacea established by 
Latreille in 1804, proposes the name Leveillia in its place. I find the opinion of 
those whom I have consulted to be divided as to the advisability of this change, 
and, as the two words although so similar are actually distinct, I do not at present 
see my way to adopt it. In his paper Mr. Newton gives an interesting history 
of this genus and of the neighbouring genus Bellerophon. He refers it to the 
Family PleurotorriMriidse, but it seems to be so allied to Bellerophon that it must 
follow the family in which that genus is placed. 
1. Porcellia bifida, Sandberger, sp. PI. XXXI, figs. 12 — 14. 
1841. Belleeophon Woodwaedii, Phillips (not Martin). Pal. Foss., p. 107, 
pi. xl, fig. 201. 
? PoECELLiA WooDWAEDii, Salter, MS. In the Vicary Collection. 
1853. Pleueotomaeia bifida, Sandherger. Verst. Ehein. Nassau, p. 185, pi. xxii, 
figs. 10, 10 a, b. 
1854. PoECELLiA WooDWAEDii, 3£orris. Catal. Brit. Foss., p. 289. 
1867. — — Etheridge. Quart. Journ. Greol. Soc, vol. xxiii, 
pp. 628 and 647. 
1889. — BIFIDA, Whidborne. Geol. Mag., dec. iii, to), vi, p. 30. 
Description. — Shell rather large, discoid, of rather rapidly increasing volutions, 
only slightly involute. Spire sunk so low beneath the highest point of the body- 
1 1837, Sowerby in Murchison's ' Sil. Syst.,' p. 604, pi. iii, tig. 15 ; and 1840, Sowerby, ' Greol. 
Trans.,' pi. liii, fig. 30. 
2 1891, R. B. Newton, ' G-eol. Mag.,' dec. iii, vol. viii, p. 202. 
