120 THE LIAS AMMONITES. 



small Brachiopods belonging to the genera Leptana, Spiriferina, Thecidium, Bht/nchonella, 

 and Terebratula, together with a number of Gastropods and Lamellibranchs, amounting to 

 upwards of 150 species. The Zeptana-hed forms a remarkable stratum, and was found 

 by Professor E. Deslongchamps to occupy the same stratigraphical position at Curcy, 

 la Caine, and other localities ;n Normandy, as it does in Somersetshire and Gloucester- 

 shire. The following note, January, 1862, from my learned friend Thomas Davidson, Esq., 

 P.R.S., explains the discovery of the Lias LeptcBiice : " When at Boulogne, in 1847, 

 M. Bouchard received a parcel of fossils from the Lias of Pic de St. Loup, among which 

 were several specimens of a small Leptana, and about the same time I received a small 

 parcel from Mr. C. Moore, among which I recognised two or three species of Lias Leptana, 

 which M. Bouchard and myself described, for the first time, in the 'Annals and Mag. of 

 Natural History ' for October, 1847. The discovery of the Lias Leptance is therefore 

 due to M. Bouchard and Mr. Moore. It was my description and pubhcation of these 

 species which first directed public attention to the subject." 



In Yorkshire the lower zones of the Upper Lias attain a remarkable development, 

 and have long been found to contain jet-rock and alum-shale, and an immense number 

 of organic remains in a fine state of preservation. I shall select two from among the coast 

 sections which afford the most instructive exposures of these beds. The first is the cliffs 

 and scars at Saltwick, south of Whitby. My old and esteemed friend, the late Professor 

 John PhilHps,^ made a sketch of this locality, which I introduce with a few additions, as 

 a faithful outUne of this instructive bay, whose bold promontory and conspicuous island, 

 formed of dark Lias, offer uncommon facilities for examining the whole section, and collect- 

 ing from each bed its characteristic fossils. In descending from the encircling cliffs to the 

 great hollow below, in which the alum-works were situated, we pass over — (1 and 2) the 

 thick capping of the lower shales and sandstones, with remains of plants ; (3) the dogger, a 

 rough, uneven rock, with much ferruginous material in the mass, overlying (4) the Leda 

 oyw;;«-bed, which characterises the top of the alum-shale, and in which Ilarpoceras 

 bifrons, Harp. Lythense, Phylloceras heterophyllum, Fhjll. subcarinatum, Stephanoceras 

 commune, Stephan. jibulatum, Stephan. subarmatmn, and several other species of our list 

 are found. This bed is about 34 feet thick, and overlies (5) a lumpy irregular band of 

 nodules ; beneath this (6) another bed of dark-grey alum-shale, containing an irregular 

 band of nodules, but not many fossils, about 34 feet thick, and forming the lowest 

 stratum worked for alum. It rests upon (7) a flat bed of ironestone, 4 inches thick, and 

 very persistent in its character. Beneath the ironstone is (8) a bed of hard, dark alum- 

 shale, 16 to 18 feet in thickness, which contains a great number of Belemuites 

 entombed in two seams of shale, the one three feet below the ironstone, the second a 

 foot from the bottom of the bed. Belemnites vulgaris, Bel. subtenuis, Bel. tubularis, 

 Bel. lavis. Then follows (9) an irregular band of calcareous nodules, lumpy, 

 spheroidal, or flattened, one foot thick. Beneath is (10) a dark, firm shale, with some 



1 'Yorkshire Coast,' 3rd edit., p. 144, 1875. 



