Art. XXIII. 



-Con/ribntions to tlic Pahwntology of the 

 Older Tertiary of Victoria. 



Lamellibranchs — Part I. 

 (With Plate XII.) 



By G. B. Pritchard. 



[Eead 8th November, 1894.] 



By far the greater number of our Eocene Lamellibranclis"~haTg" 

 been described by Professor R. Tate of the University of 

 Adehiide, and much credit is due to him for the treatment they 

 have received at his hands. The Rev. J. E. Tenison Woods takes 

 the next position, with a large number of species to his credit. For 

 the remaining few we are indebted to the labours of Professor 

 Sir F. McCoy, Professor Hutton, Professor Zittel, and Mr. R. 

 M. Johnston. Since the above gentlemen wrote there have been 

 very few new species added to this class, and as I have been 

 fortunate enough to procure a few which are in want of names I 

 will proceed to give their diagnoses. 



Trigonia tatei, sp. nov. 



(Plate XII., figs. 1. 2, 3.) 



Shell thick, rotundate rhoml)ic, somewhat convex, the antero- 

 posterior diameter only diftei'ing in length from the umbo-ventral 

 by about one or two millimetres ; anterif)r margin broadly 

 rounded, ventral margin nearly straight or very slightly convex, 

 posterior margin nearly straight abruptly truncated making an 

 angle of 145" with the hinge line, post-dorsal margin straight or 

 slightly angled medially. Posterior slope convex, and (ji-namented 

 with from 6 to 9 radiating obtusely rounded ribs, the siphonal 

 ridge being by far the strongest and widest, interspaces wider 

 than the ribs and showing the concentric lines of growth, 

 ribs spinulosely ornamented, when worn generally nodulose, 

 occasionally smooth ; on the slope immediately under the dorsal 

 margin [escutcheon] there are live very faint thread-like ribs 



