A. S. Green — The Permian Beds of S. Yorkshire. 99 



the Trias to tlie Tertiaries ; but I have been unable to refer the shell 

 under consideration to any of these genera. 



Our dernier ressort then appears to be in the genus Bostellaria. 



There are more than 70 species of fossil shells referred to this 

 genus, ranging from the Neocomian to the Tertiaries, although some 

 of these may belong more correctly to the genus Aporrhais. 



The shell in Bostellaria has " an elongated spire ; the whorls are 

 numerous, flat ; the canals long, the posterior one running up the 

 spire ; outer lip more or less expanded, with only one sinus, and 

 that close to the beak." ^ 



The fossil on Plate III. agrees very fairly with the above diagnosis. 

 The spire is elongated, the whorls are numerous (probably not fewer 

 than fourteen, but about one inch of the apes of the spire is 

 lost) ; the sutures are not depressed, and the whorls are flat (not 

 tumid, as in Chemnitzia Woodivardii) . The fine spiral stri^ (with 

 which the whorls are ornamented) are confined to a narrow band 

 nest the suture upon the upper border of each whorl, as is the 

 case in the modern Bostellaria curta and other species. The last 

 whorl is twice the breadth of the preceding whorl. The outer lip 

 is espanded, nearly semicircular in form, and smooth-edged; the 

 anterior canal nearly one-fourth the entire length of the shell (a 

 small portion of its estremity is wanting) ;. a slight ridge along the 

 border of the penultimate whorl may possibly indicate the posterior 

 canal, which in many species of Bostellarim exhibits a well-marked 

 ridge along one or more of the whorls — even to the apes in some 

 species. Fine lines of growth are the only other ornamental 

 markings upon the surface of the shell in addition to the spiral striae 

 along the sutural border of each whorl already referred to. The 

 length of the last whorl, including the anterior canal, probably 

 equalled the length of the entire spire when the termination of both 

 the spire and canal were perfect. Length of actual specimen 

 preserved 1^ inches. Probable length when perfect 9 inches. 



Believing, as I do, that this shell is really the representative of a 

 new species of Cretaceous Bostellaria, I have ventured to name it 

 Bostellaria Pricei in honour of its discoverer, in whose cabinet the 

 original specimen is preserved. 



II. — On the Method of Formation of the Pbkmian Beds of 

 South Yokkshire. 



By A. H. Green, M.A., F.G.S, 



PEOFESSOE Eamsay in a recent paper ^ put forward the notion 

 that the Magnesian Limestone and its associated beds of the 

 north-east of England were formed, in part at least, by chemical 

 precipitation in an inland sea. Given such a sea, without outlet, 

 and with streams flowing into it holding in solution the necessary 

 salts (bicarbonate of lime and sulphate of magnesia would answer 

 the purpose), it is clear that by continued evaporation a state of 



^ Woodward's Manual of the MoUusca, p. 105. 



* Quart. Journ. Geol. Soc. of London, vol. xxvii., p. 245. 



