38 CEETACEOUS PELECYPOEA 



dcL BUnomya, A. Adams, 1864, (Ann. and Mag. Nat. Hist., vol. xiii, p, 207). 

 This was proposed as a sub-genus for sucli forms as have the surface of the 

 shells lamellar, like 'NecBva proper, but possess a small triangular cartilage-pit, and 

 two lateral teeth in the right valve. — N, fllh.J Philipinensis, Hinds. 



9b. Cardiomya, A. Adams, 1864, (ibid, p. 208) ought apparently to include 

 the species of Necera which have the surface radially ribbed, like N. Gouldiana of 

 Hinds. 



H. and A. Adams, in their work on the genera of Mollusca (ii, p. 369,) class 

 Theora next to NecBra^ apparently following the suggestions of Hinds regardina* 

 the relation of these two genera, Hinds having first described a few species of 

 Theora under the generic name of Necera. I have examined the animal of some 

 species of Theora, which chiefly live in brackish water along the coast of the Bay 

 of Bengal, and found them to be allied to those of the Scrobigulariibm, to which 

 family the genus must be referred. On account of a very marked relation of the 

 fossil FalcBomya to Theora, I shall treat of the former also in the last named family, 

 and the same applies to a peculiar recent shell called Tlectodon by Carpenter. 



10. Forornya, Eorbes, 1844. Shell oval, equivalve, ventricose, gaping poste- 

 riorly, covered with a scabrous epidermis, below which the surface is either punc- 

 tated, or granular, or finely spinulous, the unevenness of the surface ajopearino^ to 

 give firm attachment to the epidermis. Hinge with a strong tooth in the left valve, 

 and two smaller ones in the right, and in each with a posterior groove, in which 

 is lodged a small cartilage ; fulcra prominent for the attachment of a more or less 

 strong ligament ; pallial line submarginal, and posterior sinus small. 



Deshayes (Paris fossils, 2nd edit., p. 248,) correctly,* I think, suggests, that 

 the fossil shells which Sowerby called Thetis, and which name has been adopted by 

 H. and A. Adams in preference to that of Eorbes, are thoroughly distinct from 

 those belonging to the present genus. Of the former I shall treat in the Veneribm 

 (sub-family bosiniinm). 



The first Foromyce as yet known are only from cretaceous rocks, though very 

 little doubt exists that the genus is much older. Of recent shells there are not much 

 more than about half a dozen species known (see A. Adams in Ann. Mag. Nat. 

 Hist., xiii, 1864) ; they are deep water shells, and have been found in European and 

 Chinese seas. The form of the siphons and of the foot, equally with that of the shell 

 and its hinge, necessitate, as already pointed out, the classification of this genus in 

 the coRBULiNJE, in preference to that in the anatinin^. Foromya is not identical 

 with JSuchaiHs, Becluz, but Umbla Xorenii of Loven is identified by Sars, and 

 by other very able observers of the North-European marine fauna, with the type 

 species Foromya granulata, N y s t. Gray formerly placed Emhla (as distinct from 

 Foromya) in the Lasseib^. 



11. Azara, d'Orbigny, 1839. Shell like Corhula, right valve with two obscure 

 teeth, separated by a broad pit, in which fits the process of the left valve supporting 



* Subsequently (ibid. p. 408) be alludes to tbe. great similarity of Sowerby 's Thetis d^nd. Poromyi^, but I do 

 not tbink tbat tbis statement bas more weisrbt tbau tbe former. 



