Mr Ether idge on Fossils from Bowen River Coalfield. 293 



possess consists of examples with the shell preserved, and in 

 a few cases retaining their internal characters in a fine state 

 of preservation. 



It is strange that out of the large series forwarded by Mr 

 Jack so few specimens should retain traces of the septum, 

 reniform impressions, and other anatomical details. The 

 usual condition under which the dorsal valves of >S^, Clarkei 

 are presented to us in the Queensland Collection is shown by 

 figs. 18a, 19, and 20, a flat, bevel-edged, more or less oval 

 silky shell, and although viewed from the interior in each 

 case, no trace of the marked characters of figs. 21 and 23 are 

 visible, but on the contrary there is, in the place of the strong 

 cardinal boss and septum, an oval gap in the shell substance. 

 This discrepancy between such examples as figs. 18a and 21 

 I believe can be accounted for simply by decortication, be- 

 cause on several specimens before me I find traces of much 

 shelly matter remaining, and which, if wholly preserved, 

 would bring the shell up to the thickness required to make it 

 correspond with fig. 21 or 23. A more complete demonstra- 

 tion may be made by means of figs. 20, 24, and 25. In fig. 

 25 we have a young example, in which the septum, alar 

 ridges, and dental sockets are clearly visible. In fig. 20 these 

 are all absent, but we have left the front termination of the 

 right reniform impression (fig. 20), and again, in fig. 24, we 

 have a further advance in traces of the great central depres- 

 sions and the actual presence of the reniform scars, clearly 

 leading up to figs. 21 and 23. I think that, putting together 

 the information deducible from these several specimens, all 

 the examples similar to figs. 18a and 19 may be fairly said 

 to have intimate connection with the more perfect figs. 21, 

 etc. On the receipt of Mr Jack's collection, I was at once 

 struck with the appearance of fig. 2-3, and sought the opinion 

 of Mr Davidson on the subject. In reply he sent me two 

 corresponding valves (fig. 21) forwarded to him some time 

 ago from New South Wales by the Eev. J. E. T. Woods, F.G.S., 

 and which had been placed by Mr Davidson in his cabinet 

 under the name of Strophalosia Woodsi (m. s.). On working 

 through the Queensland Collection, it became apparent from 

 the form, structure of the shell, and general characters of 



