GINGLYMACONCHA. UNIONIDZ. 325 
elxxiv.; Stw&rm. Deutsch. Faun. vi. no. 2. t. a, 6, c.; Flem. 
Edinb. Encycl. vii. 88 ; Wood, Gen. Conch. i. 104. t. xix. 
f. 3, 4; Dill. Desc. Cat. 49 ; Turt. Conch. Dict. 106. 
Mya ovalis, Pult. Cat. Dorset. 27. t. xii.f. 4; Donov. Brit. 
Shells, t. Ixxxix.; Mont. Test. Brit. 31. 
Mya batava, Mont. Test. Brit. 36; M. & R. Trans. Linn. 
Soc. viii. 37; Wood, Gen. Conch. 1. 103. t. xix. f. 1, 2. 
Unio Pictorum, Lam. Hist. Nat. des Anim. sans Vert. vi. 
part. 1. 79. 
Mantle dirty luteous ; the orbicular muscle saffron, fringed 
with saffron coloured, but black behind ; the fringes of the 
respiratory tubes pale ; branchize dirty saffron ; lips transpa- 
rent, saffron-coloured ; abdomen silvery white; the foot 
bluish-dusk, its extremity luteous. 
The usual form of this shell is elongate, shghtly compressed 
and gradually narrower behind. Some specimens are much 
compressed, especially posteriorly, and others resemble Unio 
ovalis in their external form ; but may generally be distinguished 
by the broad excavation on its lower aspect, which is very 
rarely wanting. 
As Linneeus has cited the figures of Lister and Bonanni, I feel 
perfectly assured that this species is his Mya Pictorum; and 
having examined Montague’s specimen of Maton and Racket’s 
Mya Batava, I am equally certain that it is utterly impossible 
to separate it from this species. 
Lamarck’s Unio Batava is common in the Seine, and is de- 
cidedly a distinct species. 
The “ Musculus fluviatilis & fluvio Tamesi ad Battersey,”’ 
Inst. Hist. Nat. Conch. t. exlix., is merely a distorted variety 
of this species: Lister’s specimen is in the British Museum. 
I have twice found between Lambeth Stairs and the Red- 
house in Battersea Fields, specimens much resembling Lis- 
ter’s, and I have received similar varieties passing into the 
common one, from my worthy friend, the Rev. J. Bulwer, who 
found them plentifully in the river Bure, and in a stream 
near Erpingham in Norfolk. 
Unio Pictorum is common in the Thames, the New River, 
