490 BRITISH PAL-LOZOIC FOSSILS. [ LaMELLIBRANCHIATA. 
gently convex; posterior one falcate, extending nearly as far as the edge of the shell, with few, distant, radiating 
ridges ; the other rounded, and with four or five obscure ridges ; beak narrow, much elevated, incurved. Surface 
radiated with about six strong, narrow, obscurely rugged ridges; between each pair of which are three smaller, 
the middle one largest, and alone extending to the beaks along with the six primary ridges, which they there 
nearly equal in size; intervening spaces flat or slightly concave, about as wide as the ridges. Width from beak 
one inch one line, proportional length {%;, depth of one valve *. 
This strongly-marked species is easily recognised by the great distance which the primary radiating 
ridges are asunder, and the flat, smooth spaces between them. I cannot see on what grounds M. de Ver- 
neuil proposes to distinguish his P. Kokcharofi, of the Permian marls of Archangel, which seems to me, 
judging from his figure and description, to be identical, except perhaps in having more ridges on the ear. 
Position and Locality —Rare in the carboniferous limestone of Lowick, Northumberland. The original 
Trish locality was Manor Hamilton. 
Explanation of Figure.—P|. 3. E, fig. 1. Left valve; natural size. 
Genus. BAKEWELLIA (King). 
Gen. Char.—Aviculoid, obliquely aliform; right valve smaller than the other; anterior side small, sepa- 
rated from the body of the shell by a strong byssal sinus; beaks separated by a distinct triangular cardinal area, 
tapering to the ends of the hinge-line, marked with longitudinal sulci angulated under the beak, crossed by 
several transverse cartilage pits; teeth diverging, variable, generally two short diverging teeth on the anterior 
side, and one or two posterior ones running along the hinge nearly to the extremity; anterior and posterior ad- 
ductor impressions strongly marked, connected by the simple pallial scar; an accessory impression over each 
adductor. . 
This closely resembles the mesozoic genus Gervillia, but is separated by the strong anterior adductor. 
BAKEWELLIA CERATOPHAGA (Schlot. Sp.) 
Ref. and Syn. = Mytilus ceratophagus Sehlot. Akad. Miinchen. Vol. VI. t. 5. f. 2.= Avicula id. Goldf. Pet. 
Germ. t. 116. f. 6.= Bak. id. King, Perm. Foss. t. 15. f. 24 to 27.4 Avicula antiqua Miinster, Gold. Pet. 
t. 116. f. 7. + B. bicarinata King, Perm. Foss. t. 14. f. 41, 42. 
Dese, (Var. Ceratophaga vera.)—Obliquely aliform, body of the shell evenly tumid, most so from the beak 
(which projects prominently beyond the hinge-line) to the posterior end, which is elliptically rounded ; posterior 
wing pointed, extending slightly beyond the end of the shell, flattened and abruptly defined from the body of 
the shell by a narrow, highly-inclined slope; posterior margin deeply sinuated near the dorsal portion, oblique 
towards the end of the shell ; anterior lobe small, triangular, obtusely pointed at the apex, separated by a strong, 
very oblique byssal sinus from the body of the shell. Surface marked with small sharp, irregular, imbricating 
striz parallel with the margins ; cardinal area very narrow, nearly parallel-sided. Length of hinge from ante- 
rior to posterior end five lines, proportional length of posterior wing ;%, greatest width of the body at right 
45 5 
angles to middle of posterior slope ;%,; width of posterior wing ;, (rather small specimen) from beak to poste- 
rior end }*; depth of left valve ;\,, width of cardinal area about ;. 
Var. bicarinata King. Only differs from the above type by having the tumid anterior lobe bisected nearly 
in the middle by a slight sulcus from near the beak, not seen in right valve. A specimen was presented by 
Prof. King to the Woodwardian Museum with B. antigua under the same name, 
Var. antiqua. The type specimens of this species in Count Miinster’s collection are clearly marked 
examples of the first var. ceratophaga in striation, pointed end to the posterior wing, and its deeply concave 
posterior edge, &e. 
