338 TESTACEOUS MOLLUSCA. 
Adacna leviuscula, plicata, vitrea and colorata of Fichwald’s ‘Fauna 
Caspio-Caucacisa’ to this genus. 
On Mya (p. 19). Compare M. alba of Agassiz in the Neufschatel 
Transactions (vol. 2, pl. 1, f. 8) with M. arenaria. See, too, M. precisa 
of Gould (Pr. Bost. vol. 8, p. 215). 
M. cancellata, p. 20, t. 13, f. 60... M. semistriata, p. 20, t. 10, f. 16. 
On Anartna (p. 20). This genus requires much emendation. 
However averse one may feel to the introduction of modern genera, 
the necessity of its dismemberment must be acknowledged by any one 
possessed of a tolerably large collection of Lamarckian Anating. In 
addition to those divisions already suggested, viz. Periploma, Thracia 
and Lyonsia = Osteodesma (of the last of which the A. membranacea, 
p. 28, is probably a member), it is advisable to adopt the three 
following :— 

NEAERA, Gray. 
Transverse, swollen, attenuated and gaping in front, fragile, very 
slightly inequivalve; umbones strengthened within by a rib on the 
anterior side ; cartilage process spatulate, in each valve with an obsolete 
tooth in front, and a front lateral tooth ; pallial sinus very shallow. 
To this genus must be referred the A. costata, p. 23, and the 
Corbula rostrata, p. 46. Hinds (Z. P. 1843) has described a 
N. hyalina, elegans, Gouldiana, Singaporensis, casta, concinna, 
didyma, rosea, Philippinensis, trigona, iridescens, opalina and lata ; 
to these may be added our British species cuspidata, costellata, and ab- 
breviata. Forbes, also, has described (Z. P. 1843) a N. attenuata, and 
Loven (Ind, Scan. Mol.) a N. vitrea and obesa. 
ANATINELLA, Sowerby. 
Ovate, equivalve, subequilateral, slightly beaked and subtruncated in 
front, rounded behind. Hinge consisting of a cartilage fixed to a spoon- 
shaped process in each valve, behind which are two rather elongated 
primary teeth ; 2 lateral scars, no pallial sinus. 
The A. Nicobarica (Mya angulata, Spengl. Sk. Nat. 11.— Anatinella 
Sibbaldi, Sow. Gen.), p. 23, is the type of this group. 
MYODORA, Gray. 
Trigonal, rounded behind, attenuated and truneated in front; one 
valve flat, the other convex; interior pearly; cartilage narrow, tri- 
angular, between 2 tooth-like ridges in the flatter valve, with a free 
sickle-shaped ossicle ; pallial line sinuated ; structure like Anatina. 
A, brevis (p. 24), ovalis (p. 25), Pandoriformis (p..25), crassa (p. 25), 
and Pandora striata (p, 50), belong to this group. Several other 
