Cbenaxula. MOLLUSC A. PERNADjE. 391 



2. G ? acuta — Ovate lanceolate, oblique, narrow, depressed, slightly cur- 

 ved; anterior extremity acute; teeth in the hinge variously disposed.— 

 Sower. Min. Conch, t. dx. f. 5.— In Calcareous Sandstone, at Collyweston. 



3. G. aviculoides Obliquely ovato-lanceolate, curved; both extremities 



pointed ; hinge-line nearly half the length of the shell ; hinge-teeth few. — 

 Sower. Min. Conch, t. lxi. and t. Dlxvi In Green Sand and Oolite. 



Gen. CRENATUL A.— Shell subequivalve, depressed ; hinge 

 with numerous pits, without teeth for the reception of the 

 ligament. 



1. C. venlricosa Ovate, elongated, ventricoso-carinated ; posterior* side 



impressed ; beaks pointed — Sower. Min. Conch, t. ccccxliii ? 



2. C. Listen.— List. Conch, t. cccclxvii. f, 34-6 — Park. Org. Rem. iii. 220. 

 t. xv. f. 5 — Upper Oolite. 



3. C. producta Park. Org. Rein. iii. 221. t. xv. f. 6, 7 — " In a Marl-pit 



near Shefford, in Bedfordshire." 



Gen. INOCERAMUS. — Shell inequilateral, irregular ; hinge 

 a marginal, subcylindrical, transversely sulcated callus, sup- 

 porting a ligament ; beaks conspicuous at one end of the 

 hinge. 



1. I. Cuvieri — Obovate, curved, convex, with transverse, distant, obtuse 



waves ; posterior side concave, with a small lobe near the beak Sower. 



Linn. Trans, xiii. 457- — Mant. Suss. 213. t. xxvii. f. 4. t. xxviii. f. 1-4 — Ca- 



tillus Cuvieri, Cuvier, Oss. Foss. ii. 251. t. iv. f. 10 Sower. Min. Conch. 



t. ccccxli. f. 1 — In Chalky 



2. I. Brongniarti. — Oblong, gibbose, with large transverse undulations ; 

 anterior side angular, lobed ; posterior side flat, truncated and smooth ; beaks 



small, curved, and pointed — Mant. Suss. 214. t. xxvii. f. 8 Sower. Min. 



Conch, t. ccccxli. f. 2, 3 In Chalk. 



3. I. mytiloides — Equivalved, elongated, depressed, with slight irregular 

 waves ; convex and obtuse towards the beaks ; hinge-line oblique ; anterior 

 side produced ; beaks short — Mant. Suss. 215. t. xxviii. £ 2 — Sower. Min. 

 Conch, t. ccccxlii. — In Chalk. 



4. I. cordiformis — Equivalved, heart-shaped, transversely and interrupted- 

 ly waved ; beaks large, incurved ; anterior side angular — Sower. Min. Conch, 

 t. ccccxl. — In Chalk. 



5. I. concentricus — Unequivalved, ovate, one of the beaks much produced, 

 incurved — {Park. Geol. Trans, v. 58. t. i. f. A.)— Sower. Min. Conch, t. cccv. 

 — In Chalk Marl. 



6. I. sulcatus — Unequivalved, oblong, with prominent beaks, and about, 

 nine large longitudinal plaits; beak of one valve, incurved, acute.— (Park. 

 Geol. Trans, v. 59. t. i. f. 5.)— Sower. Min. Conch, t. cccvi.— In Chalk Marl. 



7. I. Lamarkii.-— Valves equal, very convex, with a few obscure longitudi- 

 nal undulations, and distant transverse ridges ; surface covered with nume- 

 rous concentric striae ; posterior slope subdepressed ; anterior side lobate, ex- 

 panded; hinge nearly transverse — (Park. Geol. Trans, v. 55.) Mant. 



Suss. 214. t. xxvii. f. 1 In Chalk. 



