84 Gatliff and Gabriel: 



Obs. — In size the shell attains to about 9x9 mm. Our specimens 

 are smaller, as also are others from Stewart Island, kindly sent to- 

 ns by Mr. II. Suter, named Thyasira flexuosa, Montagu. The aiea 

 of distribution of this species is very wide; it occurs in European. 

 West Indian, Japanese and Australasian seas. Fossil in European 

 Neocene and Pleistocene; and Tertiary, Florida, U.S.A. 



Very many more references to the species could be cited ; those 

 given indicate the difficulty that is found in classifying these small 

 shells, and the difficulty is enhanced when, as in this species, indivi- 

 dual specimens vary considerably in form and size. 



It may be questionable as to whether the name Thyasira, com- 

 municated by Leach to Lamarck, and attached to a named and 

 well-known shell, his generic name apparently not having been' 

 previously published, is sufficient to establish the genus. Lamarck 

 does not adopt it, but classes it in his genus Amphidesma, where- 

 it is misplaced. 



CUNA EDENTATA Verco. 



1908. Cuna edentata, Verco. T.R.S., S.A., vol. xxxii., p.. 

 357, pi., U, f. 1-3. 

 Hab. — Same as preceding species. 



Obs. — Size of type: Antero-posterior, diam., l.G; umbo-ventral,. 

 1.9 mm. The shell much resembles G. concentrica, Hedley, but that 

 species has the inner ventral margin crenulated ; in the above species- 

 it is smooth. 



Cuna comma, Verco. 



1908. Cuna comma, Verco. T.R.S., S.A., vol. xxxii., p.. 

 357, pi. 17, f. 29-31. 

 Hab. — Same as last-named species. 



Obs. — Size of type: Antero-posterior, diam., 2.6; umbo-ventral. 

 3.2 mm. Obliquely pyriform. Concentrically ribbed. Inner 

 ventral raargin smooth. 



Cuna concentrica, Hedley. 



1902. Cuna concentrica. Hedley. Mem. Aust. Mus., vol. 

 iv., p. 315, f. 55. 



1908. Cuna concentrica, Hedley. Verco, T.R.S., S.A., vol. 



xxxii., p. 357. 



1909. Cuna concentrica, Hedley. May, P.R.S., Tas., for 



1908. p. 54. 

 Hab. — Torquay. 



