157 



illary like Chimeera, but without a triturating tubercle ; structure 

 homogeneous ; outer surface reticulated. Sp. Psaliodus compressus, 

 Egerton. It is supposed to be from the London clay. 



" On the Geology of the Neighbourhood of Bayonne." By Samuel 

 Peace Pratt, Esq., F.R.S. 



After noticing the published descriptions of the geological struc- 

 ture of the neighbourhood of Bayonne, by M. Dufrenoy, M. le Conte 

 D'Archiac, and M. de Colligno of Bordeaux, the author proceeds 

 to detail the result of his own observations in that locality in 1842. 



Bayonne, situated at the junction of the rivers Adour and Nive, 

 about four miles from the coast, is nearly surrounded by low hills of 

 sand and gravel, those on the north side of the river being appa- 

 rently a prolongation of the beds of pudding-stone and gravel which 

 form a ridge extending from Tarbes to Pau, in a direction nearly 

 east and west to the coast. The gravel and alluvium on the south 

 diflfers in mineralogical character, and forms a thin coating to a suc- 

 cession of deposits of sand, clay and impure limestone which rise to 

 the south-west towards the coast. The sandy limestone, which is 

 composed almost entirely of Lenticulites compkmatus and Nummulites 

 hiarritzana {N. elegans ?), with a few fragments of shells, chiefly 

 Pectens, forms for a short distance the north bank of the river 

 Nive, rising at an angle of 20° or 30°. It is for the most part 

 covered up by beds of sand and variously coloured clays, resembling 

 the plastic clay. The gravel is very variable in thickness and con- 

 tains no flint, but is chiefly composed of rounded and irregular 

 masses of sandstone very like the Bagshot sandstone. The country 

 in this direction has been much disturbed. 



About four miles in a south-west direction from Bayonne is the vil- 

 lage of Biarritz, near which there is an excellent coast section. The 

 sands and clays have nearly thinned oflP before reaching the cliffs 

 which rise from beneath the dunes, about a mile and a half to the 

 north-east of the village, and vary in height from 20 to 80 feet. In 

 a small bay called the Chambre d' Amour the beds are well seen, con- 

 sisting of strata of sandy argillaceous limestone, from a few inches 

 to five or six feet in thickness, all containing fossils in greater or 

 less abundance. Several faults occur between the first rise of the 

 strata and the village, by which the upper beds are repeatedly 

 thrown to the level of the shore. The organic remains vary con- 

 siderably in the several beds throughout the series, but lenticulites 

 and nummulites characterize the whole ; corals are numerous, but 

 shells more rare. In the disturbed strata at Biarritz all the Echino- 

 dermata, which are very numerous, have been found. 



Among the fossils at the Chambre d' Amour are, besides the fora- 

 minifera before mentioned and numerous corals, the following mol- 

 lusca : — Pholadomya margaritacea, Venus transversa. Pinna marga- 

 ritacea, Spondylus radula, Gryphcea vesicularis ? Pecten arcvatus 

 and tripartitus, Solen strigilatus, and Teredo articulata ; also Turri- 

 tella carinifera, Pyrula nexilis and Triton appeninum, Ditrupa suhulata 

 and several Serpula accompany them. 



