258 GINGLYMACONCHA. PHOLEOBIADZ. 
Mytilus pholadis, Mill. Zool. Dan. iii. t. Ixxxvii. f. 1-3; Gmel. 
Syst. Nat. 3357. 
Bissomie, Cuv. Rég. Anim. ii. 490. . 
Saxicava pholadis, Lam. Hist. Nat. des Anim. sans Vert. v. 
502. 
Inhabits the northern seas of Europe. 
I have described this species from three or four specimens 
taken between the islands of Bute and Arran in the collection 
of Mr. Knox of Glasgow ; it had all the external characters of 
Mytilus, but as he permitted me to open one of the specimens 
with the animal in it, I can assure my readers that it had no 
byssus. 
Genus 8. H1aTELua. 
Hiatella, Daudin, Cuvier, Lamarck. 
Cardita, Bruguiére. 
Shell equivalve, oblong, entire, scarcely gaping behind, closed 
before ; umbones simple, placed near the anterior margin ; 
cardinal ligament external, hinge-shaped ; hinge with one tooth 
in each valve; the valves behind the cardinal ligament connected 
together by a membrane. The tracheal tubes of the animal 
long, cylindric, and connected together. 
HIIATELLA SPINOSA. 
Shells whitish, transversely striated and wrinkled (with its 
left side longest, the apex truncated) ; with two spiny lines 
extending from the umbones to its hinder margin. Length of 
the shell one inch. 
Solen minutus, Lenn. Syst. Nat. xii. 1115 ; Chem. Conch. vi. 
t. vi. f. 51, 52;, Mont. Test. Brit. 52. t.i.f. 4; 2 
Trans. Linn. Soc. viii. 47; Flem. Edinb. Encycl. vii. 89 ; 
Wood, Gen. Conch. i. 139. t. xxiv. f. 5,6; Dill. Desc. Cat. 
69; Turt. Conch. Dict. 161. 
Mya arctica, O. Fabr. Faun. Grenl. 407. 
Cardita arctica, Brug. Dict.no.11; Encycl. Méthod. t.ccxxxiv. 
fA. a2 6. 
Mytilus preecisus, Mont. Test. Brit. 165. t. iv. f. 2. 
Miatella, Daud. Bosc. Coq. ui. 120. t. xxi. 
