CEPHALOPODA. | UPPER PALZOZOIC MOLLUSCA. 553 
BELLEROPHON DucHASTELLI (L’ Ev.) 
Ref. and Syn.—L’Eveillé, Mém. de la Soe. Géol. de France, t. 2. f. 8,9; de Kon. Anim. Foss. 
Bel. t. 27. f. 6. 
Desc.—Discoid, laterally compressed, greatest thickness at the margin of the umbilicus, from whence 
the sides converge to the narrow, prominent, obtusely carinated periphery, being gently concave in the middle 
near the keel, and very convex at the obtusely rounded edge of the umbilicus; umbilicus large, with steeply 
sloped sides; mouth elongate, subtrigonal, with a very small supplemental lobe at each inner angle. Surface 
crossed with subregular, obtuse, strong, subimbricated ridges (five in two lines at seven lines in diameter), 
very strongly arched (more than a semicircle) on the sides, and meeting the keel on each side at an angle of 
about 25°. Diameter eight lines, proportional width of mouth %, length of mouth @, diameter of umbilicus 25. 
This remarkable species does not seem to have been noticed in Britain before. 
Position and Locality.—Rare in the carboniferous limestone of the Isle of Man. 
BELLEROPHON Dumontr (d’Or?.) 
Ref—@ Orb. Monog. Belleroph. t. 2. f. 16 to 20. 
Casts apparently of this remarkable, elongate, narrow, species occur occasionally at Lowick. They are 
intermediate between B. cornu-arietis and B. apertus in appearance, the whorls being entirely exposed as in the 
former, but much less widely separated, and increasing gradually as in the B. apertus, and with an umbilicus 
little larger than that of that species. 
BELLEROPHON HIULCUS (Mart. Sp.) 
Ref. and Syn. = Conch. Nautilus? hiuleus Martin, Pet. Derb. t. 40. f. 1, 2.= Bellerophon hiulcus Sow. Min. 
Con. t. 470. f. 1.4 B. bicarenus. 
Desc.—V ery globose ; periphery and sides regularly rounded, moderately expanded towards the mouth, the 
reflected corners of which have a minute, partly closed umbilicus ; mouth transversely reniform, broadly rounded 
in the middle, with narrow rounded sides ; band very broad, flat, sharply defined on each side by a sharp thread- 
like keel, varying greatly in strength, and sometimes partially effaced, leaving the band apparently bounded 
by impressed lines. Surface marked with very numerous, close, slightly irregular imbricating ridges, separated 
by wider flattened spaces, arching from the minute umbilicus at an average angle of 50° on each side of the keel, 
near which, however, their extremities are abruptly arched backwards, so that the angle at the point of junction 
is often not more than 20°; band either smooth or marked with strongly arched, imbricating lines of growth. 
Width and diameter of small specimen one inch one line, umbilicus too small to be measured ; about seven 
transverse ridges in two lines near the mouth and keel, width of band one line. 
This species is remarkable for the very great width of the band, which although always wider than that of 
any other species, varies a little in this respect. I have no doubt that the B. bicarenus is only founded on 
specimens of the present species, having the bounding keels very strongly marked. In both Sowerby’s and 
Martin’s figures a keel marked with double lines is represented on one side of the band, though obsolete on the 
other, and this is by no means uncommonly the case, and some specimens which have the keels so strongly 
marked as to answer to the B. bicwrenus in some parts, have the band bounded apparently by impressed lines 
(as stated by Sowerby) from their absence in other parts. 
Position and Locality——Rare in the carboniferous limestone of Derbyshire. 
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