DIMYAIRA. 141 



rounded, gaping at the extremities ; hinge with one tooth, which 

 is somewhat complicated, or two teeth, of which one of them is 

 simple, with an anjoining deltoid hollow, which is oblique, and 

 prominent within ; no lateral teeth ; ligament internal, attached 

 in a pit. 



The want of lateral teeth, at once distinguish the shells of this genus from 

 those of the Mactra. 



Lutraria elliptica. — The Oval Lutraria. Plate XVIII. 

 fig. 4. Oblong-oval, nearly smooth, having a few concentric, 

 nearly obsolete wrinkles ; and some diagonal stricB at the ends of 

 the valves ; of a fine yellow, or greenish-brown : inside white. 

 Five inches broad. Inhabits the seas of Europe. 



There are two sections.—* Shell transversely oblong. 

 ** Orbicular. 



Section IV. — Crassipedes. — The mouth united in front, 

 or partly so ; foot thick, posterior i shell gaping when closed. 



TRIBE I. — MYARIA. 



Shells having a broad spoon-like tooth in each valve, or in 

 one only ; gaping at both extremities, or only at one end. 



Genus 57.— ANATINA.— ZamarcA. 



Generic Character. — Transverse, subequi valve, gaping at 

 both valves, or in one only ; no cardinal teeth ; one broad pri- 

 mary tooth in both valves, projecting interiorly ; a lateral plate 

 running obliquely under the primary teeth. 



Sometimes there is a fissure or suture extending from the apex, giving the 

 appearance of a second plate or rib. 



These shells form a connecting link between the Mactra and Mya*. 



Anatina decUvis. — The Sloping Anatina. Plate XVIII. 

 fig. 5. Oval, thin, brittle, a little gaping near the end, where 

 it is truncated, slightly wrinkled concentrically ; yellow sand- 

 colour. Two inches broad. Inhabits the British seas. 



Genus 58. — MYA Linnaeus. 



Generic Character. — Transverse, gaping at both ends, with 



