THE 
GEOLOGICAL MAGAZINE. 
NEW SERIES. DECADE Ill. VOL. VI. 
No. VIII.—AUGUST, 1889. 
ORIGINAL ARTICLIEHS. 
AUN Ee St 
I.—Tue Lias Martusrone or Titron, LeicestersHIRe. 
By E. Wizson, F.G.S., and W. D. Cricx, 
With Paleontological Notes by E. Wiuson, F.G.S. 
(PLATE X.) 
(Concluded from the July Number, p. 305.) 
Carpinia Sutatteri1, Walford, 1878. Plate X. Figs. 1, 2. 
1878. Isocardia? Slatteri, Walford, ‘‘On some Middle and Upper Lias Beds in the 
Neighbourhood of Banbury,’’ Proce. Warwick Nat. and Arch. Field Club, 
1878, p. 49. 1879. Jsocardia, sp. in reprint of same paper, pp. 16, 20, 
fig. 5 in plate. 
Description.—Shell trigonal, thick ; umbones large, angulated and 
terminal, ending in acute points, which curve downwards, forwards, 
and a little outwards; the sides of the shell, triangular in form, 
slightly excavated and highly inclined to the areas, are bounded by 
prominent carinz, an acute carina separating the side from the 
slightly concave triangular area in front, and a more rounded carina 
separating it from the slightly convex triangular area behind. The 
valves are marked with strongly defined and somewhat sinuous sub- 
imbricating lines of growth at wide and fairly regular intervals, 
between which may be discerned numerous fine lines of growth. 
Lunule small and deep. Cardinal tooth elongated, oblique and pro- 
minent in the right valve, small and triangular in the left. Anterior 
lateral tooth of right valve obtusely conical and very prominent, 
received into a deep socket in the corresponding valve, immediately 
above the impression of the anterior adductor muscle; posterior 
lateral tooth in left valve elongated, longitudinally grooved and 
attenuated towards the umbo; muscular impressions deeply sunk 
into the substance of the shell, the anterior triangularly ovate, the 
posterior oval-oblong; pallial line not discernible in specimens 
examined ; ligament external, groove for its insertion elongated, 
shallow and curved concentrically with the dorsal margin of the 
shell. Height of shell, 18 to 25 mm.; breadth, 21 to 29 mm. 
Note.—This shell has somewhat the form of an Opis, and is very 
like Opis Ferryi, Dumortier (Dépdts Jurassiques, pt. 3, p. 264, 
pl. xxx. fs. 4-6) ; but it differs from that shell by its more strongly 
curved outlines, absence of longitudinal ribs, and larger size. 
Possibly that form, as well as certain other trigonal bicarinated 
shells having imbricating growth layers—and the hinge characters 
DECADE III.—VOL. VI.—NO. VIII. 22 
