324 GINGLYMACONCHA. UNIONIDZ. 
Soc. vin. 39 ; Wood, Gen. Conch. i. 105. t. xix. f. 5; Dell. 
Dese. Cat. 50; Turt. Conch. Dict. 106. 
Mantle pale fuscous luteous ; the orbicular muscle whitish, 
often externally or entirely saffron; the fringe blackish; the 
branchiz dirty saffron, inclining to luteous ; the lps hyaline 
or dirty luteous; the abdomen whitish; the foot white or 
saffron. 
This species, of which I have never seen any continental 
specimens, lives in slowly flowing waters ; it is found abundantly 
in the Thames, the New River, in the Croydon and Surrey 
canals ; very plentiful im the river Avon above and at Bath ; 
and is likewise found in the river Mole in Surrey. 
Those from the Avon and Mole are thicker than those from 
the other localities, and are generally covered with a very black 
or deep brown epidermis. Young specimens are always more 
or less tinted with pale green. 
Unio ovalis is often placed in cabinets as the U. Pictorum, 
from which it may readily be distinguished by its wedge-shape, 
by the abruptness with which it is narrowed behind, and by 
the oblique notch in the tooth im its left valve. 
2. Unio Pictrorvum. 
Shells with their valves ovate-oblong, anteriorly rhomboidally 
attenuated, the extremity obtusely acute; the cardinal teeth 
wrinkled and serrated; the right one lamelliform, the left ex- 
cavated beneath, receiving the right one; the epidermis olive, 
yellowish or pale fuscous. Length four inches; height one and 
three-quarters, and more rarely two inches. 
Mya Pictorum, Lister, Anim. Angl. t. ii. f. 30; App. t.i. f.4; 
Conch. t. cxlvi. f. 1. exlvn. f. 3; Pet. Gaz. t. xen. f. 9; 
Valentine, Mus. t. xiv. f. 15; Bonanni, Recr. t.ii. f. 40, 
41; Ginann. Op. Port. t. iv. f. 16; Linn. Faun. Suec. 
2129; Syst. Nat.xu. 1112.n0.28; Murray, in Amen. Aead. 
vil. t. ul. f. 6; Schroét. Fluss. t.iv. f. 6; Penn. Brit. Zool. 
iv. 79.t. xlii. f. 17 ; Da Costa, Brit. Conch. 228. t. xv. f. 4; 
Brug. Encyel. Méthod. cexlviui.f.4; Donov. Brit. Shells, t. 
