96b YORKSHIRE TYPE AMMONITES— II Jan. 



96. AMMONITES AUREOLUS, Simpson 

 (Plate XCVI) 



172. Armmonites] aureolus. [M. Simpson, 1855, P- 94-] 



For Original Description and Additional Details see Vol. I, p. 28b. 



Remarks 



In the collection of the late Dr. Clarkson is a specimen with label 

 A. aureolas, which agrees in diameter, colour and characters with 

 Simpson's description. Therefore this specimen may reasonably be 

 regarded as the holotype, and the Whitby Museum example (PL XXVIII) 

 as a paratype. Hence an illustration of the Clarkson specimen and 

 a revised notice is necessary. 



The outer whorl of the Clarkson specimen is distinctly less than 

 J the diameter, but that of the Whitby Mueum example is barely so. 



Proportions : Clarkson Coll. 24, 20, 21, 60. 



Whitby Mus. Coll. 29, 24, 25 ? 58. 



Narrow whorls, great regularity of ribbing and distinct peripheral 

 sulci are the special features of the Clarkson specimen. The Whitby 

 Museum example, besides differing in proportions, has not the same 

 regularity of ribbing and is only just subsulcate. The Clarkson specimen 

 would appear to be the young of the form figured by Blake as Arietites 

 tar deer escens, especially if Blake's figure is somewhat reduced, as seems 

 to be likely. The Whitby Museum example would fall into another 

 category — the subsulcate series : it would come between E. modestam 

 and E. spiratissimum in the annexed list (p. 96c). There is a larger 

 example in the Clarkson collection which falls into the same position : 

 it may be listed as the holotype of a new species with the Whitby Museum 

 example as a paratype. 



The Clarkson collection is now housed in the Jermyn Street Museum, 

 having been acquired by the Geological Survey of England. 



