214 
CONCHIFERA. 
Trigonellites. 
In the Lias, Langar, Nottinghamshire, and Saltford and 
Weston. 
This is not the CJnio concinua of Sowerby —that shell being more 
regularly ovate and considerably shorter in proportion than Cardinia 
soutula , which is also more acuminated and inclining upwards at the 
posterior side than P. concinna. 
10. Cardinia crassissima. —The Very Thick Cardinia, 
ph LXXIV. fig. 8. 
Pachyodon crassissima . Stutehbury, Ann. Nat. Ilist. VIII. 
P* 483, pi. 9, fig. 7. Unio crassissimus. Sowerby, II. p. 
121, pi. 153. 
Ovate, very thick; beaks much incurved and acute ; hinge¬ 
line considerably arcuated, with a large triangular cardinal 
tooth fitted into a pit in the opposite valve, and a very 
broad, curved, and long lateral tooth in each valve, with 
grooves for their reception in the opposing valves; ante¬ 
rior side rather short and rounded; posterior side long, and 
slightly narrowed at its lower angle; beak convex, the base 
nearly straight; surface with rather regular, equidistant, 
transverse lines of growth ; muscular impressions deep. 
The Inferior Oolite, Dundry, Somersetshire. 
11. Cardinia crassiuscula.—T he Thickened Cardinia, 
pl. LXXIV. fig. 18. 
Pachyodon crassiusculus . Stutehbury, Ann. Nat. Ilist. Supp, 
VIII. p. 483, pl. 9, fig. 8. I r nio crassiusculus , Sowerby, II. 
p. 191, pl. 185. Pullastra antiqua , Phillips, Geo. York, I. 
pl. 13, fig. 1G. 
Regularly elliptical, sub-compressed ; valves very thick; 
beaks depressed, and projecting beyond the elliptical lino, 
with fine, very slightly incurved points; hinge-line un- 
dulous, much thickened; muscular impressions deep ; pallial 
impressions strongly defined; both sides almost equally 
rounded; back and base moderately arcuated ; surface smooth, 
with a few equidistant, remote, shallow lines of growth. 
In the Lias at Langar, Cheltenham, Blue Anchor, Somer¬ 
setshire, and Robin Hood's Bay, Yorkshire. 
12. Cardinia IIybrida.—T he Mongrel Cardinia, pl. 
LXXI V. fig. 19. 
Pachyodon hyhridus , Stutehbury, Ann. Nat. Ilist. VIII. 
Supp. p. 482, pl. 9, figs. 3, 4. Unio hyhrida. Sowerby, II. 
p. 123, pl. 154, fig. 2. 
Cuneiform, sub-triangular ; hinge-line curved ; beaks 
closely approximating; the lunule elongated, lanceolate, and 
deeply impressed; anterior side concave below the beaks, and 
rounded beneath ; posterior side considerably arcuated from 
the beaks to the base, which is concave ; surface smooth, with 
transverse, rather deep furrows, or lines of growth. 
The Lias at Langar, Nottinghamshire, and near Cheltenham. 
Sub-Division II.—With one or two lateral teeth. 
Genus XXXVIII.— T)OXAX.—Linna>us. 
Shell transverse, trigonal, equivalve, inequilateral; outer 
surface generally covered with a thin horny epidermis; ante¬ 
rior side for the most part the shorter; loft valve with two 
more or less distinct cardinal teeth ; right valve with only one 
cardinal tooth, which is generally cloft at its extremity ; later¬ 
al teeth variable, either one or two very minute aud remote ; 
two muscular impressions in each valve, that of the mantle 
with a large sinus; ligament external and short. 
1. Donax trunculus. —The Little Stock Donax, pl. 
LXXXIX. figs. G, 7. 
J). trunculus . Brown, Ill. Rcc. Conch. Brit. p. 97, pi. 39, 
fig. 11. 
Transversely oblong, somewhat compressed ; beaks small; 
anterior side nearly straight above, and rather contracted; 
posteriorly rounded ; surface smooth, with fine radiating, lon¬ 
gitudinal stria?; internal margin crenulated. 
The Mammiferous Crag, Bramerton. 
Genus XXXIX.— TRIGONELLITES.—Parkinson. 
Shell slightly rounded, trigonal, thick ; gapingon each side ; 
anterior sido nearly straight; posterior side gently waving; 
hinge-line quite linear; destitute of teeth ; with an appro¬ 
priate surface on the anterior margin of each valve, for the 
attachment of the cartilage externally ; no visible muscular 
impressions ; substance of the shell very thick. 
1. Trigonellites latus. —The Broad Trigonellites, pl. 
LXXV. fig. G. 
T. latus. Parkinson, Org. Rem. III. p. 184, pl. 13, figs. 
9, 10, 11. 
Sub-triangular; anterior side concave below the beaks, and 
rounded beneath ; posterior sido nearly straight, with a longi¬ 
tudinal shallow furrow extending from the beaks to the side ; 
basal lino arcuated; surface smooth, with concentric shallow 
lines of growth ; beaks acute ; inside of the valves porous. 
The Kimmoridge Clay, Whitchurch, Buckinghamshire, and 
Southroy. 
2. Trigonellites politfs.— 1 The Polished Trigonellites, 
pl. LXXII* fig. 1G. 
T. politics. Phillips, Geo. York, I. pl. 5, fig. 8. 
Considerably elongated transversely, its breadth being more 
than twice its length ; anterior sido extremely short, and 
nearly in a straight line with the very obtuse beaks, which 
are quite terminal; posterior side lengthened, with a very 
wide, shallow, obliquely, longitudinal furrow, emanating from 
the back of the umboncs, and terminating on the margin, which 
is a little cleft. Surface smooth, with minute, shallow lines 
of growth; back nearly straight; base a little curved. 
The Oxford Clay, Yorkshire and Wiltshire. 
3. Trigonellites antiquatus.— The Antiquated Trigo- 
nollites, pl. LXXII.* fig. 12. 
T. antiquatus . Phillips, Geo. York, I. pl. 3, fig. 2G. 
Transversely oblong-ovate; anterior side very short, rounded, 
and hardly extending beyond the obtuse beaks ; posterior side 
long aud rounded, a deep furrow extending from behind the 
beaks, aud terminating on the margin ; beneath this a shallow 
furrow ; back arcuated, with many rather wide, transverse, 
equidistant furrows ; the other portions of the shell with wide- 
set, concentric, very narrow furrows, crossed by several 
radiations ; basal line a little concave in the middle. 
