328 
DEVONIAN FAUNA. 
Description. — Shell of moderate size, subglobose, horizontally symmetrical. 
Spire and umbilicus similar, concave, wide, of few (two or three) whorls. Whorls 
rather rapidly increasing, especially near the mouth, long-oval in section, being 
highly convex on upper and lower sides, flattish inside, and moderately and 
decreasingly convex on the back ; bearing (in the cast) a few indistinct longi- 
tudinal inequalities, one of which on the centre line of the back tends to become a 
sharp keel near the mouth. Mouth large, very narrow, sub-lunate. Test and 
surface unknown, but shell- structure probably massive. 
Size. — Height about 27 mm., width 27 mm. 
Localities. — There are three specimens in Mr. Vicary's Collection, and two in 
my Collection, from Chircombe Bridge. 
Remm^ks. — These fossils are all internal casts and, therefore, nothing can be 
learnt of the character of the shell itself except inferentially. It is, however, so 
like the figure given by Beushausen that I have no hesitation to referring it to the 
same species. The restoration given by F. A. Romer of his shell is utterly unlike, 
having many more whorls, but Beushausen states that this is incorrect, and the 
fragment of the shell itself figured by Romer seems to agree with our shell. 
Affinities. — It differs from B. bisnlcatus, F. A Romer, ^ by being larger, higher, 
and less trilobed, and from B. glohatus, Sowerby,^ by having a larger umbilicus, 
and less expanding mouth. 
B. radiatus, Bichwald,^ seems somewhat similar in general shape, but its spire 
appears to be more open ; from its general appearance I think it cannot be identical. 
It is covered with an elaborate ornamentation of which the English fossils pre- 
serve no trace. 
B. apertus, Sowerby,* which, though in England a Carboniferous shell, is quoted 
by d'Orbigny^ from the Eifel, is very similar, but it is marked with much more 
decided spiral elevations and depressions. 
B. plenus, Billings/ shows a distinct keel on the cast. 
I am in much doubt whether the small shells doubtfully referred by Phillips to 
B. Wenlockensis, Sowerby, may belong to this species. As, however, they are very 
much smaller and appear to have a more convex back I have thought it safer 
not to unite them at present. 
1 1843, F. A. Eomer, ' Verst. Harzgeb.,' p. 32, pi. ix, fig. 1. 
2 1839, Sowerby in Murch. ' Sil. Syst.,' p. 604, pi. iii, fig. 15, and pi. iv, fig. 50. 
^ 1860, Bichwald, ' Lethaea Eossica,' p. 1074, pi. xli, figs. 1 a — c. 
4 1824, Sowerby, ' Min. Coucb.,' p. 108, pi. cdlxix, fig. 1. 
5 1840, de Ferussac and d'Orbigny, ' Hist. Nat. Cephal.,' p. 190, (Belleropboii) pi. i, fig. 1, and 
pi. iii, figs. 4 — 6. 
6 Billings, ' Palaeozoic Fossils,' vol. ii, pt. 1, p. 62, pi. v, figs. 8, Sa,Si. 
