294 



PROCEEDINGS OF THE GEOLOGICAL. SOCIETY. [Feb. 18, 



Nor is this bed, so valuable in the abundance of its palgeontologieal 

 evidence, less suggestive of physical facts. The thin and interrupted 

 bed which I consider to be the representative of the Marlstone, the 

 pebbles and small boulders imbedded therein, the perforations of the 

 Lithodomi, the masses of shells here and there collected into hollows, 

 as it were, of the underlying rock, the Serpulce covering the shells 

 and pebbles, and the very intermixture of Upper Lias species, all 

 point to a sea-bottom upon which, for a long period, little or no de- 

 posit took place ; the water-worn fragments which lie upon it, on 

 the contrary, indicating that, during that period, previously formed 

 strata were again destroyed. From what I have seen of the junc- 

 tion of the Middle with the Upper Lias, both here and at Glaston- 

 bury in Somersetshire, I have been led to believe that, immediately 

 previous to the deposition of the Upper Lias, some disturbing cause 

 for a time changed the direction of the currents which had brought 

 here the mud and sand of the Lower and Middle divisions, and that, 

 in place of continuing gently to lay down these deposits, the action 

 of the water was for a time, and over certain districts, confined to 

 the destruction of beds previously formed and consolidated*. 



Serpula, two species. 



Apiocrinites ? 



Pentacrinus ? 



Holectypus hemisphaericus, Desor. 



Thecidea Moorei, Dav. 



Terebratula punctata, Sow. 



subpunctata, Dav. 



nuirrismalis, Lam. 



quadrifida, Lam. 



Moorei, Dav. 



■ cornuta, Sow. 



Edward si i, Dav. 



Rhynchonella tetrahedra, Sow. 



serrata, Sow. 



subconcinna, Dav. 



furcillata, Theodor. 



Moorei, Dav. 



cynoeephala, Richard. 



acuta. Sow. 



Spirifera rostrata, SchJoth. 



Walcotti, Sow. 



Lingula, sp. 



Perna,.sp. 



Lima punctata, Sow. 



antiquata, Sow. 



Pecten dentatus, Sow. 



textorius, Schloth. 



. sp. 



Hinnites velatus. Goldf. 

 Gryphaea Maccullochii, Sow. 



Gryphrea gigantea, Sow. 

 Myacites unionides, Goldf. 



, two other species. 



My tikis, sp. 



Modiola, several species. 



G-oniomya, sp. (aspera, El her id gc. MS.). 



Isocardia, sp. 



Cypricardia, sp. 



Ceromya, sp. 



Cardinia concinna, Stutchb. 



cuneata, Stutchb. 



Listeri, var. hybrida, Stutchb. 



Cardita, sp. 



Unicardium cardioideum. Phi 11. 



Sanguinolaria vetusta, Phi 11. 



cuneata. 



Mytilus hippocampus, Y. $ B. 

 Cardium truncatum, Sow. 



, sp. (Dayii, Etheridge. MS.). 



Area, sp. 



Cuculla?a insequivalvis, Goldf. 



Pholadomya ambigua, Sow. 



Lithodomus, sp. 



Trochus G-audryanus, D Orb. 



monoplicus, D 1 Orb. 



epulus, D' Orb. 



Emylius, D Orb. 



Eolus, D Orb. 



Maria?, D Orb. 



* Since the above passage was written, I have found a notice of this bed, which 

 I had previously overlooked, in a paper by Buckland and De la Beche, " On the 

 Geology of the Neighbourhood of Weymouth, &c." It shows clearly to what 

 formation these beds were in those days assigned, and that the conglomerate-bed 

 and its meaning had been studied years ago by those eminent observers. (See 

 Geol. Trans. 2nd ser. vol. iv. p. 31.) 



