Mr Etheridge on Fossils from- Bowen River Coalfield. 291 



alar ridges. Septum strong and ridge-like, extending for 

 more than two-thirds the distance between the cardinal boss 

 and the front margin, terminating in a small button. Imme- 

 diately under the boss is a deep depression, divided in the 

 middle line by the septum, and in which are situated the 

 dendritic adductor muscular impressions. This depression is 

 separated by a transverse ridge running across the valve from 

 a second depression similarly divided by the septum. The 

 reniform impressions are narrow, semilunar, much incurved 

 and abrupt at their front termination, and bounded outwardly 

 by a deep groove or linear depression following their course. 

 The internal bevelled edge is marked with very fine granules 

 or pustules and small veinings, being the indications of the 

 vascular system. The shell has a silky appearance, and when 

 weathered or decorticated, the shell-substance is marked by 

 a series of fine, wavy, vertical lines. The valve is exter- 

 nally ornamented with a number of close, concentric, scaly 

 laminae, and similar spines to the ventral. A series of spines 

 are also placed along the hinge of the ventral valve (fig. 33), 

 erect, and graduating outwards from the umbo. 



Qls, — This interesting species is known to us under two 

 conditions — internal casts of the ventral valve in sandy-mud- 

 stone, and dorsal valves retaining more or less of their shelly 

 matter. Examples with the valves united, retaining the true 

 shell, I have not seen ; but that both conditions I have placed 

 under the name Strophalosia Clarkei belong to one species, 

 will, I think, be self-evident, after a careful study of the 

 figures given. Further, the specimens occur together at the 

 same locality. 



The history of Strophalosia Clarkei is a brief one. It was 

 originally described by my father as a Productus, from indif- 

 ferent material in the Daintree Collection, and the external 

 characters defined. Subsequently Professor De Koninck 

 placed under this name a shell in the W. B. Clarke Collec- 

 tion, and described it in his N'ew South Wales work. In my 

 " Catalogue " I follow both these authors in placing the spe- 

 cies under the genus Frodicctus. 1 had not then enjoyed an 

 opportunity of examining specimens. 



To return to the fossils. Let us first examine the internal 



