CXXXV111 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



is unquestionably treated with an evident desire to arrive at the 

 truth. Pleuromya Scotica, GervilliaMaccullochii, Pentacrinus robustus, 

 and Isastrcea Murchisonii are new species added to the fossil fauna 

 by Dr. "Wright, who also states that the Gryphcea Maccullochii (Sow- 

 erby) is the true Gryphcea Cymbium of Lamarck : as determined from 

 the observation and comparison of the Pabba specimens, it is in his 

 opinion a Middle Lias species, both in England and France. 



I have hinted in the preceding remarks that I should have again 

 to notice the question, mooted by Dr. Wright, of a proposed modi- 

 fication of the position assigned to the sands of the Inferior Oolite 

 by English geologists. I had then in view the paper by Professor 

 Buckman on the Oolitic Rocks of Gloucestershire and North Wilts. 

 It is gratifying to observe that the two important sections used as 

 illustrations for this paper are the result of surveys made by the 

 professors and students of the Royal Agricultural College of Ciren- 

 cester, as they are thus a practical exemplification of the importance 

 of combining geology with agriculture — a subject so forcibly dwelt 

 on by our late friend Mr. Trimmer. After noticing the labours and 

 reviewing the opinions of preceding writers on the Oolites, and more 

 especially on the lowest part of the series, Professor Buckman 

 declares himself opposed to the views of Dr. Wright, and considers 

 that he has not produced sufficient evidence for associating the so- 

 called " Sands of the Inferior Oolite" with the Lias. He admits indeed 

 that some of the shells from the fossiliferous sands are peculiar, and 

 have sometimes (especially a few of the Ammonites) a Liassic aspect, 

 but at the same time contends that the greater portion of the fauna, 

 including the local and non-migrating Mollusca, is characteristically 

 oolitic, and that the two more characteristic Liassic Ammonites, on 

 which especially Dr. Wright relied, were not merely " extraneous " 

 fossils, to use the phrase of Mr. Austen, but actually obtained from 

 the true Lias, far below the sands in question. The cause of tins 

 mistake is supposed by Professor Buckman to have originated from 

 the decomposed state of the surface of the Lias here, and the fact 

 that it is masked by an overflow of the sand from above, so as to 

 have led Dr. Wright to think that the fossils were in the sand itself. 

 Professor Buckman deserves much credit for the pains with which 

 he must have instructed his pupils and laboured himself in working- 

 out the details of the whole oolitic series ; and it appears to me that 

 the question at issue between him and Dr. Wright is in itself in- 

 structive. To determine that a fossil is extraneous, it ought to be 

 shown that the bed in which it is found is, from its physical charac- 

 ters, incompatible with the organic conditions of its existence. The 

 physical conditions of the Liassic and Oolitic beds are different ; and 

 it might be expected therefore that they should have supported 

 many organisms peculiar to each, independently of any question of 

 age. Should, therefore, a bed exliibiting the physical conditions of 

 the Lias appear immersed in the Oolites, and in it be found a Liassic 

 fossil, it cannot be assumed that such a fossil is extraneous, however 

 its appearance may militate against our opinions of the age of the 

 deposit. Should, however, the fossil be found imbedded in a stratum 



