138 Proceedings of the Royal Society of Victoria. 



is still furthei- brought out, and to a much more marked degree, 

 by the larger shells from vSpring Creek, thus in the largest speci- 

 mens (62 mm. by 57 mm.) yet to hand froQi this locality we have 

 only eighteen concentric ridges in the ten millimetres from the 

 ventral margin. In addition, the lunule of D. densilineata is 

 larger, longer and more depressed, the umbo is more markedly 

 incurved and very nmch more inflated, and situated further back 

 from the anterior margin. Viewed from the dorsal margin the 

 outline is much more convex medially and flatter laterally. These 

 characters seem to me ample to distinguish this shell as a good 

 species. During the study of this species I have not neglected 

 to compare it with many actual examples of living species of the 

 genus. In the National Museum, Melbourne, there are upwards 

 of forty species of Dosinia, which, through the kindness of Mr. 

 W. Kershaw, I have had an opportunity of examining, and I 

 take occasion now to tender him my best thanks. Of the living 

 species hitherto examined, that which seems to me closest related 

 to D. densilineata, particularly the larger Spring Creek represen- 

 tatives, is I). la?/iellata, Reeve, from North Australia, but our 

 fossil species differs from this mainly in that the antero-posterior 

 diameter is proportionately longei-, and that the anterior and 

 posterior slopes are flatter, these charactei's giving a very 

 different aspect to the sliell. Further, the lunule of D. densili- 

 iieata is much longer and somewhat flatter, though abput the 

 same breadth, the umbo is more inflated, and the concentric 

 ridging is stouter in the umbonal region and not finely lamellose 

 as in the recent species ; medially the ornament is somewhat 

 similar in both the fossil and recent species, consisting of flat 

 concentric ridges becoming distinctly lamellose laterally, also 

 lamellosely ornamented near the ventral margin, but the inter- 

 vening grooves are shallower in the fossil shell. Mr. T. S. Hall 

 and I have also recoi'ded this species as D. johnstojii from the 

 eocene beds of Maude, and I now take this opportunity of 

 correcting that record. In view of the above it should now 

 stand as D. densilineata. A further point worthy of note in a 

 Tasmanian representati\'e of this species lent me by the Ballarat 

 School of Mines is that when somewhat slightly decorticated 

 exceedingly fine, close, and regular radial riblets are rendered 

 visible. I have also been able to determine with certainty this 



