ANNIVEESART ADBKESS OF THE PKESIDENT, Ixvii 



Ber; it appears in places to have been drilled bj boring shells ; it 

 also appears to have been furrowed by the action of water prior 

 to the deposition of the true Liassic strata, thus indicating a break 

 or interval between the close of its deposition and the commence- 

 ment of the Lias. The black shales, constituting the middle divi- 

 sion, are characterized by the well-known and peculiar shell, 

 Avicula contorta, and when the beds are more calcareous, by the 

 Pecten Valoniensis. The bone-bed occurs towards the lower part' 

 of the shales, and has been found extending as far as Penarth, 

 where it contains bones and teeth of fish, and coprolites in great' 

 abundance. It also contains much iron pyrites. But it appears 

 from Mr. Bristow's remarks that it is difficult to define with exact' 

 precision the lower Kmits of this formation, except the top of the 

 red and green marls of the Keuper, into which there is a gradual 

 downward passage. The organic remains, however, appear to be 

 distinct, particularly above the bone-bed ; and therefore there 

 appears to be every reason for considering it as an intermediate" 

 formation between the Keuper and the Lias. 



Whether there is any necessity for introducing a new name for 

 this formation, which has already received so many, is a question 

 we can hardly here discuss. But it appears, as I have already 

 stated, as well as from the conclusion of Mr. Bristow's paper, that 

 the Director- Greneral of the Greological Survey has determined 

 to adopt the name of Penarth beds as the Bi'itish synonym of 

 the Bhsetic beds, to be employed in the construction of the Gro- 

 vernment Greological Maps of our own country. As Sir Eoderick 

 Murchison admits that the word Bhsetic should continue to be 

 used in general geological parlance on account of the greater 

 thickness of those beds in the Bhsetic Alps and in Lombardy, 

 and I suppose also out of justice to priority of nomenclature, it 

 seems, to say the least, unnecessary to overburthen our scientific 

 terminology with additional synonyms. 



Lias and Oolite. ^A-^cendrng the scale of geological formations, 

 I find an important work by M. Eudes Deslongchamps entitled 

 " Sur les etages jurassiques inferieures de Normandie." The object 

 of this work is to describe the Lias and the Lower Oolitic system. 

 The first portion contains a description, in great detail, of the dif- 

 ferent beds of which these two formations are composed, their 

 mineralogical and palseontological characters, and the modifica- 

 tions which they have undergone in diff'erent districts, and the 

 passages from one to the other. The second portion contains the 

 geological and pala?ontological consideration of their beds under 

 the three following heads : — 1st, the difi'erent fossiliferous deposits 

 in great detail ; 2nd, the dislocations which the different beds have 

 undergone subsequent to their deposition ; and 3rd, the extent of 

 the different formations, and the limits of the seas during then- 

 different phases of sedimentation, with numerovis sections ; to this 

 is added an account of the extension of the different sheets of 

 water, which are indicated by the occurrence of the argillaceous 

 beds in the several districts. 



e2 



