Vol. 50.] RHJ3TIC AND LIASSIC OSTRACODA OF BRITAIN. 1G9 



present paper was of particular interest as giving a critical resume 

 of the present state of our knowledge, which it appeared was very 

 much needed, in addition to his other work. It would be desirable to 

 know how far the study of the Ostracoda throws any material 

 light upon the change between Rhastic and Lias, and whether the 

 separation was sharp or not. He also alluded to the difference 

 of opinion between Mr. Horace B. Woodward and Mr. Edw. "Wilson 

 as to where the line should be drawn. 



Dr. Henry Woodward also spoke. 



The Author, in reply to the President's question, — whether the 

 Ostracoda served to decide where the line of junction between 

 the Rhsetic and the Lower Lias actually occurs, — stated that in 

 Mr. Wilson's ' Upper-Rhsetic ' beds Darwinuld liassica (Brodie) 

 abounds, and indicates either freshwater or brackish-water con- 

 ditions : also at Westbury-on-Severn. Some sections near Bristol 

 (localities not well defined) have shown, above these beds, which 

 contain plant-remains (Naiadites), limestones with Cytheridea, estua- 

 rine or marine, and Cythere, a marine genus. This succession 

 shows that the ' Rhaetic White Lias' (Wilson) passed up into the 

 other ' White Lias ' above, by one or more passage-beds, probably 

 included by the Geological Survey in the ' Rhaetic ' series. The 

 habits and conditions of recent forms of the recognized genera 

 supply the data for determining the probable habits of the fossil 

 species. 



Q.J.G.S. No. l! 



