404 MOLLUSCA. MYAD.E. Lutraria. 



4. M. sulangulata. — Rather depressed, smooth; wider than long; nearly 

 equilateral, oblong-ovate ; an angle from the beak to the retral margin ; ven- 

 tral margin slightly restricted. — Sower. Min. Conch, t. lxxvi. f. 3. — London 

 Clay. 



5. M. lata Ovate, depressed ; retral side acuminated and truncated, 



slightly gaping. — Sower. Min. Conch, t. lxxxi — In Crag. 



6. M ? lilerata. — Transversely oval, subequilateral, convex, smooth, thin, 

 with obtuse angularly bent ridges on the central part ; angles of the ridges 

 in a longitudinal direction. — Park. Org. Rem. iii. 196. t. xiii. f. 16. — Sower. 

 Min. Conch, t. ccxxiv. f. 1 Inferior Oolite. 



7- M ? scripta. — Transversely oval, subequilateral, convex, smooth, thin, 

 with oblique angularly bent ridges on the central part ; angles of the ridges 

 in an oblique direction. — Soiver. Min. Conch, t. ccxxiv Inferior Oolite. 



8. M ? angulifera — Transversely elliptical, elongated, gibbose, with oblong 

 angularly bent ridges upon the surface, retral hall widest, gaping ; angles of 

 the ridges acute, in an oblique direction — Sower. Min. Conch, t. ccxxiv. f. 6, 

 7. — Oolite. 



9- M ? gregaria. — Obovate, convex, subdeltoid, smooth ; retrally produced 

 and truncated.— Sower. Min. Conch, t. ccclxiii— Upper fresh water Formation, 

 Isle of Wight. 



10. M. arenaria. — Sower. Min. Conch, t. ccclxiv. and t. Dxxxi. f. 2. — Nor. 

 folk and Suffolk Crag. 



11. M. depressa Obovate, depressed, very slightly gaping ; anterior side 



shortest ; beaks prominent incurved, hinge-line straight, depressed — Sower. 

 Min. Conch, t. ccccxviii.— Middle Oolite. This is probably a Panopeea, as it 

 is stated that the ligament is external and short. 



12. M. gibbosa Obovate, transversely furrowed, gibbose ; beaks prominent, 



incurved ; an teal side very short ; retral side rather attenuated and gaping. 

 Soiver. Min. Conch, t. ccccxix. — Middle Oolite. 



13. M. plicata. — Oblong, ventricose, straight, anterior side short, and trans- 

 versely plaited ; posterior gaping, truncated. — Sower. Min. Conch, t. ccccxix. 

 f. 3 Green Sand. 



14. M ? angustata Valves unequal ; transversely elongated, thin, anti- 

 quated, irregularly compressed ; extremities obtuse, gaping ; lower edge of 

 the lesser valve concave. — Sower. Min. Conch, t. Dxxxi. — Upper marine For- 

 mation, Isle of Wight. 



Gen. CXL. — LUTRARIA. — Equivalve, transverse, gaping .; 

 hinge with a broad vertical plate for the cartilage, sup- 

 porting one or two teeth on its anteal margin. 



580. L. vulgaris. — Nearly equilateral, and rounded at both 

 extremities. 



Concha longa, List. An. Ang. 170. Conch, t. xiv — Mactra lutraria, 



Linn. Syst. i. 1 126. Penn. Brit. Zool. iv. 92. t. Iii. £ 44. Mont. Test. 



Brit. 99. — Lutraria elliptica, Turt. Biv. Brit. 65 — In sand about low- 



water mark. 



Length 2\ inches, breadth 5 ; yellowish-white, with a thin close cuticle ; 



slightly striated concentrically by the layers of growth, with remote obsolete 



ridges. 



1 



