338 TESTACEOUS MOLLUSCA. 



Adacna laviuscula, plicata, vitrea and colorata of Eicliwald's ' Fauna 

 Caspio-Caucacisa' to this genus. 



On Mya (p. 19). Compare M. alba of Agassiz in the Neufschatel 

 Transactions (vol. 2, pi. 1, f. 8) with M. arenaria. See, too, M.prcecisa 

 of Gould (Pr. Bost. vol. 3, p. 215). 



M. cancellata, p. 20, 1. 13, f. 60 ... M. semistriata, p. 20, 1. 10, f. 16. 



On Anatina (p. 20). This genus requires much emendation. 

 However averse one may feel to the introduction of modern genera, 

 the necessity of its dismemberment must he acknowledged by any one 

 possessed of a tolerably large collection of Lamarckian Anatina. In 

 addition to those divisions already suggested, viz. Periploma, Thracia 

 and Lyonsia = Osteodesma (of the last of which the A. membranacea, 

 p. 23, is probably a member), it is advisable to adopt the three 

 following : — 



NE^IRA, 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, Goiddiana, 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, sub equilateral, 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. hi. — Anatinella 

 Sibbaldi, Sow\ Gen.), p. 23, is the type of this group. 



MYODORA, Gray. 



Trigonal, rounded behind, attenuated and truncated 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 



