338 MY. Wilson and Crick—The Lias Maristone of Tilton. 
of which have not been noticed—may eventually be found to fall 
under the genus Cardinia. 
This fossil was first discovered by Mr. HE. A. Walford, F.G.S., in 
the Marlstone and Middle Lias Transition-bed of Aston-le-Wall and 
Appletree, Northamptonshire, and referred to in this author’s paper 
above cited, and figured but not described in the reprint of same, 
under the name Isocardia Slattert, Walford. At that time the hinge 
characters had not been made out, and consequently the generic 
identification was made with some diffidence. Mr. Crick has since 
found an almost perfect left valve of this shell on the Hast Norton 
embankment, and Mr. Walford has kindly lent me a right valve, in 
which also, now that the matrix has been cleaned out, the hinge 
characters are clearly displayed (see Pl. X. Fig. 2). These hinge 
characters are essentially those of a Cardinia, as also is the mode of 
growth, and to that genus I therefore without hesitation refer this 
shell, and in this view Mr. Walford concurs. 
Marlstone Rock, Tilton (Hast Norton embankment). 
Pinna TriLTonensis, sp. nov. Plate X. Fig. 3. 
Shell elongated, lanceolate, anterior and posterior borders with 
nearly straight edges, but slightly convex ; with concentric longitu- 
dinal plice, which towards the umbo become broken up and 
mamuillated; the posterior half of each valve is ornamented with 
slender radial coste, which are regular and equally spaced except 
the two lower or median ones, which are more slender and wider 
apart; about half only of the radial costee reach the ventral border 
of the shell; these radial striz, where they cross the plice of growth, 
form a neat meshwork, and are as a series interrupted at intervals, 
where they take an oblique direction for a short distance so as to 
present a distorted appearance. We have two examples of this 
shell; both are incomplete, and the best-preserved specimen which is 
figured is very much compressed ; hence the materials for founding a 
species are not the most satisfactory, and the above name must be 
considered therefore as provisional. 
Marlstone Rock, Tilton (Hast Norton embankment). 
INOcERAMUS, sp. Plate X. Figs. 4, 4a. 
Shell markedly inequivalve, moderately inflated, longer than 
broad, broadly flattened posteriorly in the left valve, acuminated 
towards the umbones, which are prominent, pointed, approaching and 
recurved ; the valves are marked with irregular longitudinal ridges 
and furrows, and finer concentric lines of growth, and by rather ill- 
defined and irregular radial striz, which at their intersections give 
an irregularly mammillated and pitted aspect to portions of the shell. 
This shell differs in its form and markings from all the Jurassic 
Tnocerami with which I am acquainted; but having only a single and 
incomplete specimen, I hesitate to impose a new name. Should it 
eventually appear that we have here a new species, the name 
Inoceramus Tiltonensis might be given to it. 
Marlstone Rock, Tilton (Kast Norton embankment). 
