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zones for the lower lias, after Dr. Oppel, of Munich, and stated his 

 opinion that the Avicula contorta beds (all those black shales, sand- 

 stones, limestones, and bone beds intervening between the gray, 

 green, and red marls of the Keuper, and the lowest Ostrea beds in 

 the zone of Ammonites planorbis at the base of the Lias), were the 

 equivalents of the Upper St. Cassian beds, and Kbssener Schichten 

 of German geologists. In an equally valuable communication made 

 the following year (1861), by Mr. Charles Moore, to the same 

 Society, the views of Dr. Wright were in some points questioned, 

 and in this paper he states that these beds lying between the 

 Keuper marls and the Lower Lias are not the equivalents of the 

 Upper St. Cassian (or Triassic beds) but of the Kdssen stage, or 

 Rhoetic formation alone, and in this country were the only 

 representatives yet found of beds intervening between the Keuper 

 and the Lias, attaining in the South of Europe a thickness of several 

 thousand feet. In addition to this, from the fauna of the White 

 Lias agreeing in its general facies with the Avicula contorta beds 

 below, Mr. Moore proposed to take these beds from the Lower Lias, 

 where Dr. Wright and others had placed them, and classify them 

 with the Avicula contorta group beneath, under the term Rlicetic 

 formation. These views of Mr. Moore, in spite of a great disincli- 

 nation at first to accept the new nomenclature, have been since 

 adopted by the principal geological authorities. It is for this reason 

 that a short resume of the literature of the subject has been brought 

 before you this evening. 



Considering, then, the importance of these junction beds, every 

 opportunity should be taken of a careful examination of their 

 position and contents. With this view, and in fulfilment of a 

 promise made to you during one of our evening meetings last 

 year, I have worked out the fossils, so far as time permitted, 

 and made accurate measurements of a section of these Rhoetic 

 beds which are exposed in a cutting of the new Railway, 

 near the Weston Station. In a paper read before the Geological 

 Society of London, in the year 1867, " On the Abnormal Conditions 

 of the Secondary Deposits of the Somersetshire and South Wales 

 Coal Basin," Mr. Moore, alluding to the absence from the greater 

 part of the Bath district of the Insect and Crustacean beds, the Ostrea, 



