Hjppopodiijm. 
CONCH1FERA. 
195 
A. obscurus. Sowerby, IV. p. 12, pi. 314. 
Sub-triangular, transverse; beaks obtuse and nearly cen¬ 
tral ; anterior side rather abruptly abbreviated, and moderately 
rounded ; posterior side wedge-shaped, and attenuated below 
into an obtuse point; base gradually curved; surface smooth. 
The Magnesian Limestone, Carforth, near Leeds. 
4. Axinus angulatus.—T he Angular Axinus,pi. LXXIX. 
fig- IT. 
A. angulatus. Sowerby, IV. p. 11, pi. 315. 
Sub-triangular ; convex ; oblique ; breadth and length 
nearly equal; anterior side very short; a little curved; pos¬ 
terior side wedge-shaped, and depressed, with a ridge rising 
from the beaks and terminating on the side ; producing an ob¬ 
tuse angle on both sides; surface nearly flat, with a few lines 
of growth ; lunette ovate, pointed, and curved. 
The London Clay, Hampstead and Shoppy. 
5. Axinus sulcatus.—T he Furrowed Axinus. 
Donax sulcatus, Sowerby, Geo. Tr. 2d Ser. V. pi. 30, fig.l. 
Sub-triangular ; convex ; anterior, side short; straight for 
some distance below the beaks ; rounded below; posterior side 
wedge-shaped; acuminated; beaks incurved and approxi¬ 
mating ; surface smooth, with a few furrows; transverse to- 
wards the base, which is a little rounded anteriorly, and slop¬ 
ing from them upwards to the pointed extremity. 
The Coal Measures, Coalbrook Dale. 
6. Axinus rotundatus.—T he Rounded Axinus, pi. LXXIX. 
fig. 1. 
A. rotundatus. Brown, Tr. Manchester, Goo. Soc. I. p. 
05, pi. 0, fig. 29. 
Nearly orbicular; umbones almost central and acute, and 
remote; snrfaco smooth ; length upwards of three-eighths of 
au inch; breadth nearly half an inch. 
The New Red Sandstone, Newtown, Manchester. 
7. Axinus parvus.—T he Small Axinus, pi. LXXIX. f. 12. 
A. parvus. Brown, Geo. Trans.. Manchester, Geo. Soc. 
I. p. 65, pi. 0, fig. 30. 
Smooth, sub-triangular ; somewhat inflated ; umbones pro¬ 
minent, inflated, and contiguous ; posterior side acute, oblique, 
and elongated; anterior side short and rounded; length 
upwards of a quarter of an inch, breadth nearly three-eighths 
of an inch. 
The New Red Sandstone, Newtown, Manchester. 
8. Axinus undatus.—T he Waved Axinus, pi. LXXIX. 
fig. 9. 
A. undatus. Brown, Trans. Mancli. Geo. Soc. I. p. 65, pi. 
6, fig. 31. 
Sub-triaugular, smooth, inflated ; umbones small, obtuse; 
sides nearly equal ; anterior side rounded ; posterior side 
acute; from the centre of the valve emanates a triangular 
flexure, terminating in the basal margin ; length three-eighths, 
breadth half an inch. 
The Now Red Sandstone, Newtown, Manchester. 
9. Axinus pucillus.—T he Slender Axinus, pi. LXXXIX. 
fig- io. 
A. pucillus. Brown, Trans. Mancli. Geo. Soc. I. p. 66, pi. 
6, fig. 32. 
Triangular; smooth; beaks very prominent and nearly 
central; length one-eighth of an inch ; breadth the same. 
The New Red Sandstone, Newtown, Manchester. 
10. Axinus minimus. —The Least Axinus, pi. LXXIX. 
figs. 2, 3. 
Nearly orbicular; a little transverse ; beaks central, large, 
and produced ; hinge-line nearly straight; surface smooth : 
width something more than an eighth of an inch. 
The New Red Sandstone, Newtown, Manchester. 
Family IV.—CARDIACEA. 
Primary teeth irregular both in form and situation, and, in 
general, accompanied by one or two lateral teeth. 
Genus XIV.—P ACH Y M Y A .—Sowerby. 
Shell very thick, equivalve, transversely elongated ; sub- 
lobate, with the umbones situate near the anterior extremity ; 
ligament short, partly internal, and attached to a prominent 
process or fulcrum ; close at both extremities. 
I. Pachymya gig as. — The Giant Pachymya, pi. 
LXXVIII. figs. 11, 12. 
P. gig as. Sowerby, VI. p. 2, pi. 504, 505. Brown, Elts. 
Foss. Couch, p. 84, pi. 7, figs. 12, 13. 
Shell gibbose, ponderous, width twice its length; anterior 
side small, rounded; posterior side somewhat truncated; a 
ridge in both valves, emanating at the umbones, terminating 
on the posterior margin, gives a boat-shape to the general 
contour of the shell; umbones very obtuse, placed much to 
one side, general surface smooth, except near the basal mar¬ 
gin, where it is provided with imbricated laminae; thickness 
of the shell exceeding its length. 
Found in the Chalk at Dowlands, near Lyme Regis. 
Gen us XV.—IIIPPOPODIUM.— Conybea re . 
Shell equivalve, obliquely transverse, very thick, deep, and 
inequilateral; umbones incurved ; ventral margin situated so 
as to produce a bilobato appearance; hinge much thickened, 
and furnished with one rugged oblique tooth. 
I. Hippopodium PONDER08UM.—The Ponderous Ilippo- 
podium, pi. LXXIX figs. 20, 21. 
II. ponderosum. Sowerby, III. p. 91, pi. 250. Fleming, 
p. 420. Brown, Fits. Fossil Conch, p. 95, pi. 7, figs. 21 
and 23. 
Gibbose, rugged, thick, and ponderous; anterior lobe 
somewhat angular, and a little acute ; posterior lobe consider¬ 
ably smaller, rounded, and following the curvature of the 
umbones, forms the boundary of the cordiform pit beneath 
them, the width of which is greater than its length ; this 
heart-shaped pit is deep, and extends to the hinge tooth, and 
upon which the linos of growth are well defined, and con¬ 
tinue to the margin of the valve ; one valve is in depth equal 
to its smallest diameter, which measures about half the distance 
from the point of the anterior lobe to the beaks. 
When this shell rests upon the prominent parts of the ante¬ 
rior lobe, it bears a striking similitude to the general contour 
