Tertiary.'] 



PALEONTOLOGY OF VICTORIA. 



[Echinodermata. 



Marl 



This species is easily distinguished from P. gigas and P. com- 

 pressus by the more tumid, obtusely ovato-cordate form, and the 

 very slight depression of the anterior furrow, as well as the 

 slightness of the depression of the petaloid portion of the four 

 posterior lateral ambulacra. It occurs in some abundance in one 

 particular bed in the Waurn Ponds quarries, which will be best 

 recognised by the following section and extract from a note 

 furnished to me by Mr. W. Nelson, to whom I have dedicated the 

 species, one of the first specimens of which was found by him and 

 forwarded to me through Mr. Panton, who always takes a lively 

 interest in Natural Science : 



" The bed in which the new Pericosmus is found is almost the 

 lowest in the quarry. I have thought it desirable to send a 

 vertical section of the whole face. * * * 



"In the bed at a is a deposit of 

 hard flattened nodules of limestone, 

 firmly cemented together ; and in 

 this deposit I find the Pericosmus in 

 its natural position, with the lower 

 half generally resting on the soft 

 bed beneath the boulders ( nodules) 

 locally termed ' Flint Balls ' and 

 the upper portion embedded in the 

 flint. I have occasionally found the 

 Pericosmus in the block underlying 

 a ; but I have never discovered it in 

 any of the blocks above a. 



" The bed at b is remarkable for 

 its numerous Pectens. Sharks' teeth 

 sometimes are found here, the enamel 

 of which has an ivory appearance. 

 Cetotolites rarely found so low, and 

 when found are so much decomposed 

 that they cannot be taken out except 

 in exceedingly small fragments. 



" At c there is a strange mixture of small and irregularly-shaped 

 quartz-gravel in the limestone, and numerous fragments of varieties 

 of coral. 



[ 18 ], 





 f 



Section of Waurn Ponds Quarry. 



