Fossil Fauna, Table Cape Beds, Tasmania. 139 



feature in some of the Victorian shells, but owing to their good 

 state of preservation it is rarely noticeable ; on the other hand, 

 even with worn and decorticated examples of D.jolinsfoni, I have 

 hitherto been entirely unable to detect anything of this kind in 

 that species. The type of this species is in my own collection. 



125. Tellina cainozoica, T. Woods. 



Id., T. Woods, P.R.S.Tas., 1876, p. 113. 



Id., Tate, Lam. II., 1887, p. 164, pi. xviii., tig. 5. 



126. Zenatiopsis fragilis, sp. nov. Plate IV., tigs. 3 and 4. 



Shell very thin and fragile, elongate oblong, much depressed, 

 anterior end very short, posterioi* end much elongated. 



Dorsal mai-gin straight or slightly concave, anterior margin 

 regularly convex to about the anterior extremity, still convex but 

 more gradually so to meet the ventral margin, which is straight 

 or slightly convex and parallel to the dorsal margin from a point 

 slightly posterior to a line passing through the umbo for a 

 distance slightly in excess of half the full length of the shell, 

 thence the margin has a more gradual slope up to the posterior 

 extremity than at the anterior end, thence more rapidly convex 

 to join the dorsal margin. Anterior gape commences immediately 

 anterior to the umbos, while the posterior gape commences slightly 

 posterior to the umbos, the ventral margins of the valves being 

 in contact. Valves very slightly convex, greatest convexity 

 situated at the intersection of the antero-posterior diameter and 

 a line perpendicular to it and passing through its middle point ; 

 from this point the convex slope is more marked dorsally than 

 ventrally and only just appreciable anteriorly and posteriorly. 

 Umbo, though small, is prominent, acute and incurved, and 

 situated about one-sixth the length of the shell from the anterior 

 extremity. Surface ornamented with numerous shallow con- 

 centric corrugations of the shape above indicated, and fine, close- 

 set, concentric striations, with a few very faint radial striations 

 from the umbo posteriorly. 



Dimensions. — Type, antero-posterior diameter, 33 mm. ; dorso- 

 ventral diameter, 12 mm. ; thickness through both valves, 4 mm. 

 Largest specimen yet to hand measures 46 mm. by 17 mm., with 

 a thickness throusrh both valves of 7 mm. 



