36 



MR. E. LEONARD GILL ON THE PERMIAN 



rarely to be detected that it is of little practical use in identifi- 

 cation. The only example known to me which shows it clearly is 

 the type-specimen in the Yorkshire Museum (the Yorkshire 

 Philosophical Society's Museum at York) ; here the finely toothed 

 edge is still preserved on three or four scales which are seen from 



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the inside and are protected by being embedded in the matrix. 

 A few similarly situated scales on specimens at Newcastle also 

 show serration, but less completely. Most specimens of 

 A. glaphyrus show no clear trace of it at all. Such thin scales 



