4 Frederick chapman.- 



larger and heavier, and is no doubt referable to O. ingens. Ortmann 

 has alraady drawn attention to 0. sturtiana as being closely allied to 

 O. ingens.^ The specimen here figured is from Waurn Ponds (Janju- 

 kian), and measures 137 mm. by 112 mm. 



A smaller but still heavy shell of great thickness is found in the 

 Bailey collection from Beaumaris. It measures 120 mm. by 83 mm., 

 and the principal lamellae numler about 34. This is of Lower 

 Pliocene age. 



Distribution. — Victoria and South Australia: The Janjukian or 

 Miocene of Bairnsdale, Cape Otway, Murray River Cliffs. Also in the 

 Kalimnan or Lower Pliocene of Beaumaris, Port Phillip. 



Elsewhere. — New Zealand: Oamaru and Pareora beds (Oligocene 

 to Upper Miocene). 



Patago-nia: Upper part of Patagonian Formation and Suprapata- 

 gonian, Miocene. 



Chile: Coquimbo Beds. Pliocene. 



Fam. TRIGONIIDAE. 



Genus Neotrigonia, Cossman. 



Neotrigonia bednalli, Verco var. (Plate I., Fig. 3.) 



Trigonia margaritacea, Lam., var. bednalli. Verco, 1907,. 

 Trans. Roy. Soc, S. Australia, vol. xxxi., p. 224, pL 

 xxviii., figs. 1-3. 



Observations. — Dr. Verco regarded this form as a variety of the 

 living N. margaritacea. From its occurrence in fossiliferous beds of 

 Lower Pliocene age it can no longer be logically regarded as a variety 

 of a recent type, and therefore it appears to be more consistent to 

 give it specific rank. 



This form has been taken in some abundance in the living state 

 by Dr. Verco, who dredged it from St. Vincent's Gulf. A solitary 

 specimen was previously found by Mr. W. T. Bednall in 1865, between: 

 the Semaphore and Glenelg. 



This appears to be its first occurrence in the fossil state, and adds 

 to the increasing list of species from the Kalimnan whose descriptions, 

 were originally based on living examples found round the Australian 

 coast. N. bednalli has been dredged from 10 down to 200 fathoms. 

 Dr. Verco's description runs as follows: — 



" This variety is characterised by its vei'y compressed shape, its 

 narrow ribs, its large, oblong, plate-like spines, broader at their 

 free than at their attached ends, features which are exceedingly con- 

 stant in the very large series obtained." 



Occurrence. — In shelly sand of Kalimnan age (Lower Pliocene), 

 MacDonald's, Muddy Creek, near Hamilton, Victoria. Discovered and 

 presented by Mr. James Hay Young.s 



5. Princetown Univ. Exped., vol. iv., pt ii., 1902, p. 105. 



6. Mr. Young died on Feb. 10th, 1922. The Museum has been enrichedl 

 on many occasions by his valuable discoveries. 



