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E. W. WILLETT ON A MAMMALIAN JAW EROM 



28. Notes on a Mammalian Jaw from the Ptjrbeck Bees at Swanage, 

 Dorset. By Edgar W. Willett, B.A. With an Introduction 

 by Henry Willett, Esq., E.G.S. (Eead May 25, 1881.) 



(Communicated by the President.) 



Introductory Eemarks. By Henry Willett, Esq., E.G.S. 



The rarity of the fossil remains of mammals in Mesozoic strata 

 is a palgeontological fact so well known to the Members of this 

 Society, that it would be superfluous in me to do more than 

 allude to it. 



All needful information will be found in the exhaustive mono- 

 graph (by one of the greatest living authorities on comparative 

 anatomy, Prof. Owen) published in 1871 by the Palseontographical 

 Society. From it I gather that in 1828 Mr. Broderip first dis- 

 covered Didelphys in the Stonesfield-Slate quarry. 



In 1858 the teeth of Microlestes were discovered by Mr.^Moore 

 in a breccia of Ehsetic bone-bed and limestone filling a fissure in 

 the Mountain Limestone at Erome, in Somersetshire. 



In 1864 my friend Prof. Dawkins discovered a worn molar of a 

 Marsupial mammal in the Ehsetic beds at Watchet, in Somerset- 

 shire, called by him Hypsiprimnopsis rhoeticus (Microlestes rhce- 

 ticus). But it was to the personal energy and perseverance of 

 Samuel Beckles, Esq., E.B.S., that science was indebted for the 

 discovery of the great variety of these interesting fossils, the de- 

 scription of which occupies the largest portion of Prof. Owen's 

 work (loe. cit.). My own imagination was excited by a popular 

 account of Mr. Beckles's labours, written about 1858 by the late 

 lamented Canon Kiugsley ; and the desire for further discovery 

 caused me to pay several visits to the " Dirt-beds" at Swanage, in 

 the hope of maldng further additions to the catalogue of Mam- 

 malian remains. Although I must have spent altogether many 

 hours in search on several occasions, aided at times by local quarry- 

 men, I could never succeed; but in 1878, having learnt that. 

 Mr. Beckles had been obliged, unwillingly and prematurely, to 

 abandon his researches at a point which seemed rich in promise, I 

 obtained leave from the Earl of Eldon, on certain reasonable con- 

 ditions, to renew the inquiry at the point left by Mr. Beckles. The 

 year 1879- was too wet and stormy to allow me to carry out my 

 intention in so perilous a position. 



There are two so-called " Dirt-beds " in the Purhecks of Durdle- 

 ston Bay, Swanage. The lower one can be readily examined from 

 the shore, as it rises at varying angles from beneath the sea-level 

 until it is lost in the debris and turf above. 



The upper dirt-bed, which also crops out at a similar angle, is 

 less distinctly defined, until we reach a point about two thirds of 

 the way up the cliff, just below the commodious refreshment-room 



