11.  Cytherea gibba.  Cytherea gibbia, Lam.  Hist. 5 577.  Icon.  Chemn. 7 t. 39. f. 415. 416.

12.  Petricola rubra ?  Cardium rubrum ?  Montague.

This shell agrees in general form, teeth, and colour, with the Cardium rubrum of Montagu, but it is larger.  It was found imbedded in the seaweed and spongy-like substance that covers the Tridacna squamosa.

13.  Chama limbula, Lam.  Hist. 6 95.

This shell may, perhaps, be a variety of Chama gryphoides.

14.  Tridacna gigas, Lam.  Hist. 6 pt. 1. 105. 
Chama Gigas, Gmel.  Syst.  Nat. 1 3299. 
Icon.  Chemn. 7 t. 49. f. 495.  Ency.  Meth. plate 235. f. 1.

15.  Pectunculus radians ?  Lam.  Hist. 6 54.

16.  Arca scapha, Lam.  Hist. 6 42.  Icon.  Chemn. 7 201. t. 55. f. 548.  Ency.  Meth. plate 306. f. 1. a, b.

17.  Mytilus erosus, Lam.  Hist. 6 pt. 1 120.

This shell was described by Lamarck from some New Holland specimens, that were probably collected by Peron in Baudin’s voyage.  It is remarkable for being very thick and solid, and of a fine dark colour, with only a narrow white band on the anterior basal edge.  The edge is crenated, and the muscular impressions are very distinct, and raised above the surface, particularly that on the anterior valve, which is both pellucid and tubercular.

18.  Modiola (Tulipa ?) australis, Nob.  Modiola tulipa, var. 1.  Lam.  Hist. 6 pt. 1 111.

This Australian species will most probably prove to be distinct from the American kind; but the specimen before me does not afford sufficient materials to separate it, since there is only one water-worn valve in the collection.  It is not so distinctly rayed as M. tulipa, and the inside is entirely of a brilliant pearly purple, except near the anterior basal edge.

19.  Lithophagus caudatus, nob.  Modiola caudigera, Lam.  Hist. 6 pt. 1 116.  Icon.  Ency.  Meth. plate 221. f. 8. a, b.

20.  Meleagrina albida, var. a.  Lam.  Hist. 6 pt. 1 152.

This appears to be a distinct species from those found in the Gulf of Mexico and the West Indies, but the difference is not easy to describe.  The specimens before me, which are small, differ materially from some of the same size among the American species.  The outside is of a dull greenish-purple colour, with a few distant membranaceous laminae which are only slightly lobed, and not extended into long processes like those of Avicula radiata (Zool.  Misc. 1. t. 43.) which is the young of the American kind.  The internal pearly coat has a bright yellow tinge.

21.  Spondylus radians ?  Lam.  Hist. 6 pt. 1 192.  Icon.  Chemn.  Conch. 7 t. 45. f. 469. 470.  Ency.  Meth. plate 191. f. 5.

22.  Pecten maximus ?  Lam.  Hist. 6 pt. 1 163.  Ostrea maxima, Gmel.  Syst.  Nat. 1 3315.  Icon.  Chemn.  Conch. 7 t. 60. f. 585.  Ency.  Meth. plate 209. f. 1. a, b.

The shell before me is probably distinct from the above species, but is too much worn down to be separated from it; in its present state it seems to agree tolerably well with the species to which it has been referred.