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.