MOOEE — aexoe:m:al secondary deposits. 535 



beds are wanting in some of the abore districts. The Liassic beds 

 of Hettange are calculated by the above author at 25 to 30 metres ; 

 but in Luxembourg, in which they are in a basin-shaped depression, 

 they are thicker. 



i[. Deslongehamps, when speaking of the " Calcaire de Yalogne," 

 again refers to the InfraHas. Like its equivalent deposits at Sutton, 

 the beds are mostly unconformable, and are stated by that author to 

 be deposited in two small basins of Silurian strata, in which they 

 have a thickness of about 20 metres. The above basins have been 

 partly occupied by Triassic strata ; but towards Picauville where they 

 pass beyond the basin, they rest immediately upon the granite. 



It is thus clearly shown, not only that the Lower-Lias deposits 

 meet or repose upon an ancient coast-line in South Wales and 

 Somersetshii^e, but that precisely similar conditions prevail in the 

 continental districts just referred to, and that throughout their entire 

 length they are much metamorphosed and unconformable, whilst 

 at the same time, where the deposits are beyond the influence of 

 these interrupting conditions, they assume the normal characters of 

 the Liassic beds, and attain great thickness. 



It is under these circumstances that our continental friends have 

 adopted the division "Infralias" for the beds between the horizon 

 of GrypTicea incurva and the Keuper. To this arrangement I think 

 there are many objections, which will justify me in still retaining the 

 old landmarks for the Liassic series. The proposed division is based 

 upon deposits which are local and abnormal (and must therefore 

 necessarily be more or less arbitrary), instead of upon such sections 

 as those of Camel and Beer, in which there are types of the orchnary 

 succession and the general condition of the formation over a widely 

 extended area in the South-west of England ; and the result of the 

 adoption of their proposed classification would be that we should 

 probably have to remove three-fourths of the English Liassic series 

 from the Lower Lias to that of the " Infralias." 



Not only will there be many physical difficulties, but the j^alaeon- 

 tological conclusions upon which this division is based do not hold 

 good with the more extensive development of the Lias in this country, 

 where the series from above the '^ White Lias " are seen to be parts 

 of a connected whole. 



The proposed division of the " Infrahas " from the Lower Lias 

 has been suggested by the above-mentioned authors from the fact that 

 with them the Gryphee arquee {Grypluact incurva) is not seen to 

 commence with their ''Infrahas" fauna, and also that in these lower 

 beds they have a special fauna which does not apparently pass up 

 into those containing this shell. On the contrary, at Sutton and 

 Southerndown, and at Bridgend, the shell is found abundantly with 

 their ''Infralias" fauna, whilst at Brocastle, where that fauna is the 

 most varied, GryplicF.a incurva is the commonest bivalve, and I cannot 

 have collected less than fifty examples within a space of two or three 

 yards. It is found also at Willsbridge and throughout the Bath dis- 

 trict ; and at the same time a very large percentage of the whole 

 fauna is in actual association with Ammonites Conyheari, A. anr/ii- 



