298 MALACOZOA. TROPIOPODA. LAMELLIBRANCHIATA. 



with an epidermis, which is prolonged upon the mantle 

 and tubes. Umbones small. Hinge strong, with a 

 horizontal spoon-shaped process in the right valve, and 

 a corresponding fossa in the other. Ligament internal, 

 inserted between the fossa and spoon-shaped cavity. 

 Muscular impressions distant, large ; pallial impression 

 with a deep sinus behind. 



The Myae live immersed in sand, gravel, or mud, with 

 the broader or anterior end downwards. 



1. My a truncdta. Abrupt Gaper. 



Shell ovate, abruptly truncate behind, moderately thick, ru- 

 gose, covered with a strong yellowish-grey epidermis, which 

 extends over the mantle-tube to a great length ; the right 

 valve with a broad, thick, concave tooth projecting backwards ; 

 the left with a deep triangular depression ; the colour of the 

 shell dull white, or reddish, the inside white. Length three 

 inches and a-half, height two inches and a-half. 



In the estuary of the Ythan, near its mouth ; at Aberdeen, 

 Peterhead, Fraserburgb; Gamrie in Banifshire. In some 

 parts of Scotland, where this species is abundant, it is occa- 

 sionally used as food. 



Mya truncata. Linn. Syst. Nat. i. 1 1 12. Mya truncata. Penn. 

 Brit. Zool. iv. 78. PL 41. f. 14 ; Ed. n. iv. 159. PL 44 Mya 

 truncata. Mont. Test. Brit. 32. Mya truncata. Turt. Brit. Biv. 

 31. Mya truncata. Flem. Brit. Anim. 462. Mya truncata. Lamk. 

 Syst. v. 461 ; Ed. 2. vi. 73. 



2. Mya arendria. Sand Gaper. 



Shell ovate, rounded at both ends, but elongated and nar- 

 rowed behind, moderately thick, rugose, covered with a tbin 

 yellowish-brown epidermis, which extends over the mantle- 

 tube to a great length ; the right valve with a broad, thick, 

 concave tooth, and a small tooth-like projection from the pos- 

 terior side ; the left valve with a deep triangular depression ; 

 the colour of the surface white, reddish- white, or ferruginous. 

 Length about five inches, height three inches and a-half. 



In some parts of Scotland, as in the outer Hebrides, where 

 this species is abundant, it is sometimes used as food. It is 

 however inferior in this respect to Mya truncata. 



At Ythan-mouth, in the mud and gravel ; often very coarse, 

 distorted, with the epidermis abraded, the colour of an inky 

 black, which disappears on being exposed to the atmosphere. 



