400 BRITISH PALASOZOIC FOSSILS. [ CepHALOPoDA. 
6th Class. CEPHALOPODA. See page 306. 
ist Ord. TrrraprancuiAta. See page 307. 
Ist Family. BELLEROPHONTID. See page 307. 
Genus. BELLEROPHON. See page 308. 
BELLEROPHON BISULCATUS (0mer). 
Ref —Harzgebirge, t. 9. f. 1. 
Sp. Ch.—Discoid, of three very thick whorls, almost entirely exposed in the large deep umbilicus, each 
whorl divided into three subequal lobes by two strong, shallow, spiral furrows, the middle lobe much more 
prominent than the others, and leaving a narrow keel-like indentation in the middle of the inner margin of 
mouth, and inner face of the outer whorls; umbilical margin of the whorls very convex. Diameter of large 
specimen one inch, proportional diameter of last whorl #2, diameter of umbilicus +, width of last whorl about =. 
This species is easily distinguished from the Silurian B. trilobatus with which most Paleeontologists have 
confounded it, by its wide umbilicus, almost entirely exposing the whorls, the turns of the spire barely indenting, 
in a narrow line, the succeeding whorls. 
Position and Locality—vVery common, but ill-preserved, in the dark Devonian schists of Polperro, 
Cornwall. 
BELLEROPHON striatus (Ler. and d Orb.) 
Ref.—Cephal. t. 1. f. 11, 18, 14, 17; Bronn. Leth. t. 1. f. 11. 
Sp. Oh.—Globose, very slightly compressed ; umbilicus deep, narrow, rounded, not exposing the whorls ; 
keel strong, narrow, from which strong thread-like striz arch regularly to the umbilicus, meeting at the keel 
at an angle of 110°, about two to three times their thickness apart, measuring usually three interspaces in the 
space of two lines; mouth transversely lunate. Diameter one inch, proportional diameter of last whorl ;, 
diameter of umbilicus *, width of mouth =. 
This species is perhaps most allied to the B. tenuifascia, but has a very much thicker keel, and coarser 
striee; and from the B. costatus it differs in the more obtuse angles at which the transverse ridges meet the keel ; 
and the distinctness of this angle separates it from B. tangentialis, in which they meet the keel nearly at right 
angles. 
Position and Locality —Not uncommon in the Devonian limestone of Plymouth. 
BELLEROPHON SUBGLOBATUS (M/°Coy). 
Ref. and Syn.= Bellerophon globatus Sow. Geol. Trans. 2nd Series, Vol. V. t. 53. f. 30. (not of Sil. Syst.) 
Sp. Ch.—Internal cast globose, slightly depressed ; periphery obtusely rounded ; mouth transversely lunate, 
deeply indented by the preceding whorl, sides rounded; umbilicus very small, not exposing any part of the 
inner whorls ; sides very convex, without wrinkles. Diameter six lines, proportional diameter of last whorl ;%, 
diameter of umbilicus }°, width of mouth 4, length of mouth in middle ;;. 
This may perhaps be the internal cast of some of the small carboniferous species, but I give it a 
provisional name, to distinguish it for the present from the Silurian B. globatus, with which Mr Sowerby 
in the above volume of the Geological Transactions, and Professor Phillips in his Paleozoic Fossils, con- 
founded it, but from which it is certainly distinct, by its very minute umbilicus, not exposing a trace of 
the inner whorls, nor has it a trace of the strong transverse wrinkles of the sides of that species, in which 
the umbilicus is rather wide and exposes nearly half of the inner whorls. 
Position and Locality—Common in the sandstone of Marwood. 
