BY C. HEDLEY 435 



Australian ally is S. infa7is Smith, which occurred with it, in 5-10 

 fathoms, off the Hope Islands. iS'. isosceles is smaller, more 

 •inflated, more solid, more triangular, and is especially distin- 

 -guished by its concentric sculpture. 



THEORA. NASUTA, n.sp. 



(Plate xxxviii., figs.37-39.) 



Shell small, ovate acuminate, a little inflated, thin and trans- 

 lucent. Rounded on the ventral and anterior mai-gins, poste- 

 riorly produced and angled. Colour white. Surface smooth. 

 Length 4*65; height 3*5; depth of single valve 1-25 mm. 



Compared with Theora fragUis A Adams, this is a smaller 

 shell, proportionately shorter and more sharply beaked. It was 

 a common species at the scene of our dredgings, and I had pre- 

 viously found it as abundant, in 15 fathoiDS, off the Palm Islands. 



Davila plana Hanley. 



Mesodes7na plamtm Hanley, Proc. Zool. Soc. 1843, p. 102; id., 

 Reeve, Conch. Icon. viii. 1854, Mesodesma, PI. iii., f 16; id., 

 Hidalgo, Mem. R. Acad. Cien. Madrid, ii. 1903, p. 65. Davila 

 j)lana Dall, Trans. Wagn. Inst. iii. pt.4, 1898, p.913. 



This giegarious species lives buried in wet sand at the foot of 

 the Hope Island beach. It seems to have escaped attention as 

 an Australian native. I have gathered it at Dunk, Green, and 

 Palm Islands. 



Gastroch^na gig ante a Deshayes. 



Fistidmia gigaatea Desh., Enc3^cl. Metli., Vers, ii. 1830, p. 142, 

 GastJ'ochcena gigantea Desh., Trait, elem. Conchyl. i. 1843, p. 34, 

 Pl.ii., f.6,7,8; id., Lamy, Bull. Mus. d'Hist. Nat. xii. 1907, p.207. 



Under the name of G. laniellosa Desh., this species was added 

 to our fauna by the Challenger Expedition. Dr. Lamy shows 

 •that both names, gigantea and laniellosa, refer to the same shell. 

 In the ease of Cardiitni lobulatum, the blighting influence of the 

 Cumingian clique upon Deshaj^es has already been noticed. On 

 all the reefs of the Great Barrier this is a common shell. 



