82 REPORT — 1856. 



All the Cephalopoda of the above list are found only in the uppermost zone of the 

 Upper Lias of France and Germany, with the exception of Amm. hifrons, which 

 occupies always a lower zone, and at Frocester is contained in the nodules towards 

 the base of the sands; one gasteropod and seventeen species of Conchifera, found in 

 the Ammonite bed, extend upwards into the Inferior Oolite ; the species marked with 

 an asterisk (*) form the series which are common to the Cephalopoda bed, and to the 

 limestones of the Inferior Oolite. All the others are either Upper Lias forms or are 

 special to this bed. 



One of the Brachiopods, Bhynchonella cynocephala, is found only in the Cepha- 

 lopoda bed, whilst Terebratula suhpunclata descends into the marlstone. 



The author contended that all classes of the Mollusca are not of the same value to 

 the pakeontologist in stratigraphical geology, as some have a much wider range than 

 others ; for example, certain species of Conchifera extend through the Lower and 

 Middle Lias, others pass from the Inferior Oolite into the Cornbrash, and even into 

 the Coral rag, whilst the different zones of the Lias, and the several stages of the 

 oolitic rocks, are all characterized by distinct species of Ammonites, which are limited 

 to these different horizons of life; for this reason Cephalopoda are regarded as better 

 indicators of geological time than Conchifera; as none of the twenty-one species of 

 Ammonites, Belemnites and Nautili passed from the Cephalopoda bed into the In- 

 ferior Oolite, and were all identical with Upper Lias forms, it was inferred that the 

 Cephalopoda bed represented the Jurensis-marl of German authors, or the uppermost 

 zone of tl)e Upper Lias. 



The author further showed that the Inferior Oolite contains fourteen species of 

 Ammonites, two Nautili, one Belemnite, ten species of Gasteropoda, forty species of 

 Conchifera, ten species of Brachiopoda, eight species of Annelida, twenty-two species 

 of Echinodermata, and fourteen species of A ntkozoa, not one of which was found in 

 the Cephalopoda bed on which the Inferior Oolite immediately rests. 



The Dorsetshire sections confirm the same conclusions, but the lists of. fossils from 

 these rocks are not so complete as those furnished by the Gloucestershire sections; 

 the author had not collected many of his Dorsetshire fossils himself, and was unable 

 to decide on the stratigraphical position of many of his specimens. Ammonites Dorset- 

 ensis, Wright, has not yet been found in the Cotteswold hills, although it is most 

 abundant in several localities in Dorsetshire. 



The Cephalopoda bed is regarded as the English equivalent of the " Ores supra- 

 liassique ou marly sandstone" of M. Terquem, as developed in the department of the 

 Moselle. 



" Schiste et Marne de Grand Cour" of MM. Chapuis and Dewalque, as it occurs in 

 the Province of Luxembourg. 



"Graue Kalkstein-Bank mit Ammonites /«»'ew««" of Quenstedt, forming the bed f, 

 the uppermost of his Schwarzer Jura (Lias). 



The Jurensis-marl of Dr. Fraas, in his table of the Jura formation of Suabia. 

 The positive palaeontological evidence leads the author to group his Cephalopoda 

 bed with the uppermost zone of the Lias, specifically characterized by Ammonites 

 Jurensis and variabilis, and Rhynchonella cynocephala, and the other forty-four 

 species special to this bed ; and negatively separated from the Inferior Oolite which 

 rests upon it, by the one hundred and twenty species which appear for the first time 

 in that stage. 



Besides the forty- seven species which have hitherto been found only in the Cepha- 

 lopoda bed, there are eighteen species which are common to this bed and the Infe- 

 rior Oolite ; but these are chiefly Conchifera, which have a wide vertical range, whilst 

 the Cephalopoda, which are special to it, have a very limited distribution in time ; 

 both positive and negative evidence therefore support the conclusion that the Cepha- 

 lopoda bed and sands belong to the uppermost part of the Upper Lias, and not to 

 the Inferior Oolite with which they have hitherto been classed. 



