﻿442 DE. A. YATJGHAI^ 0^ THE FAUISTAL SUCCESSION [Aug. I908, 



and approaches nearest to a form rare in CS^ of the South- Western 

 Province and of Ravenstonedale/ 



(b) The Lithost7'otion-like Clisiophyllids of the megastoma-heds 

 and of the Carlyan Limestone agree more closely with S^ forms 

 from the South- Western Province, the Ingleborough area/ and 

 Arnside than with any D form yet known. 



In fact, the Carlyan fauna suggests S^ and not D ; the material, 

 however, is scanty and poor. 



Eeviewing the whole evidence : — The broad resemblance to a 

 Z^-C-Sj sequence is not confirmed by identity of detail. On the 

 other hand, the evidence for a D horizon is far from conclusive, 

 and the failure to find an unquestionably Yisean form in the whole 

 thickness of the ZaphrentisSleites is without parallel in fossiliferous 

 D beds. The final solution of the question of level must await 

 fresh evidence. 



Faunal Comparison of the Rush and Lane Conglomerates. 



E-esemblances : — 



An identical Zaphrentis-f&cies precedes each. 

 Michelinia succeeds ZajaJirentis as a common fossil. 



Differences: — 



The Rush Conglomerate is fossiliferous ; the Lane Con- 

 glomerate barren. 



Michelhiia megastoma is common in the Rush, but rare 

 above the Lane, Conglomerate. In the case of Michelinia 

 cf. tenuisepta the reverse is true. 



Campophyllum aff. Murchisoni and Diphyphyllum suh- 

 ibicinum abound above the Lane, and are absent from the Rush, 

 Conglomerate. 



Lithostrotion cyathoj^hylloides abounds in the Rush, no 

 Liihostrotion is met with above or below the Lane, Con- 

 glomerate. 



Chonetes cf. comoides abounds at the top of the Lane Lime- 

 stone, but is absent from the Rush Slates : papilionaceous 

 Ohonetes are, however, common in the Carlyan Limestone. 



We can, therefore, deduce no closer approximation of age than 

 is expressed within the range and abundance of the Rush-Lane 

 ZapJirentes, and this broad interval would allow of considerable 

 difi'erence of horizon. 



The abundance of small ZapJirentes usually accompanies such 

 shallow-water deposits as are liable, by no great physiographical 

 change, to pass into conglomerates or dolomites, and Michelinia 

 often survives the actual change. 



(In no small measure, the broad similarity of the Z.,-C fauna of 

 the South- Western Province to that of the Rush Slates and Con- 



■^ From material collected by Mr. Cosmo Johns. 



