214- 



CONCHIFERA. 



Trigoneixites. 



In the Lias, Lang-ar, Nottinghamshire, and Saltford and 

 Weston. 



This is not the Unto conchina of Sowerby— tliat shell being more 

 regularly ovate and considerably shorter in proportion than Cardinia 

 scutula, which is also more acuminated and inclining upwards at the 

 posterior side than P. concinna. 



10. Cardinia crassissima. — The Very Thick Cardinia, 

 pi. LXXIV. fig. 8. 



Pachyodon crassissima. Stutchbury, Ann. Nat. Hist. VIII. 

 p. 483, pi. 9, fig. 7. Unio o-assissimus. 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 CRASSinscuLA. — The Thickened Cardinia, 

 pi. LXXIV. fig. 18. 



Pachyodon crassiusculus. Stutchbury, Ann. Nat. Hist. Supp. 

 VIII. p. 483, pi. 9, fig. 8. Unio crassiusculus, Sowerby, II. 

 p. 191, pi. 185. Pullastra antigua, Phillips, Geo. York, I. 

 pi. 13, fig. 16. 



Regularly elliptical, sub-compressed ; valves very thick ; 

 beaks depressed, and projecting beyond the elliptical line, 

 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 Hybrida. — The Mongrel Cardinia, pi. 

 LXXIV. fig. 19. 



Pachyodon hylridus, Stutchbury, Ann. Nat. Hist. VIII. 

 Supp. p. 482, pi. 9, figs. 3, 4. Unio hybrida. Sowerby, II. 

 p. 123, pi. 1.74, fig. 2. 



Cuneiform, sub-triangular ; binge-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. 



rior side for the most part the shorter ; left valve with two 

 more or less distinct cardinal teeth ; right valve with only one 

 cardinal tooth, which is generally cleft at its extremity ; later- 

 al teeth variable, either one or two very minute au<l remote ; 

 two muscular impressions in each valve, that of the mantle 

 with a large sinus ; ligament external and short. 



1. DoNAx TRUNCuiiUS. — The Little Stock Donax, pi. 

 LXXXIX. figs, e, 7. 



I), trunculus. Brown, 111. Rec. Conch. Brit. p. 07, 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 XXXVIIL— DONAX.— Zin««?«s. 



Shell transverse, trigonal, equivalve, inequilateral ; outer 

 surface generally covered with a thin horny epidermis ; ante- 



Genus XXXIX.— TRIG ONELLITES.— Parii««o« . 



Shell slightly rounded, trigonal, thick ; gaping on each side ; 

 anterior side 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, fur the 

 attachment of the cartilage externally ; no visible muscular 

 impressions ; substance of the shell very thick. 



1. Trigonbllites latus. — The Broad Trigonellites, pi. 

 LXXV. fig. 6. 



T. latus. Parkinson, Org. Rem. III. p. 184, pi. 13, figs. 

 9, 10, 11. 



Sub-triangular ; anterior side concave below the beaks, and 

 rounded beneath ; posterior side nearly straight, with a longi- 

 tudinal shallow furrow extending from the beaks to the side ; 

 basal line arcuated ; surface smooth, with concentric shallow 

 lines of growth ; beaks acute ; inside of the valves porous. 



The Kimraeridge Clay, Whitchurch, Buckinghamshire, and 

 Southroy. 



2. Trigonellites politcs. — The Polished Trigonellites, 

 pL LXXIL* fig. 16. 



T. politics. Phillips, Geo. York, I. pi. 5, fig. 8. 



Considerably elongated transversely, its breadth being more 

 than twice its length ; anterior side 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 umbones, 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- 

 nellites, pi. LXXII.-* fig. 12. 



T. antiquatus. Phillips, Geo. York, I. pi. 3, fig. 26. 

 Transversely oblong-ovate; anterior side very short, rounded, 

 and hardly extending beyond the obtuse beaks ; posterior side 

 long and rounded, a deep furrow extending from behind the 

 beaks, and terminating on the margin ; beneath this a shallow 

 furrow ; hack 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. 



