Vol. 58. | JURASSIC OF THE SOUTH WALES DIRECT LINE. 745 
Rhynchonella obsoleta, Terebratula maxillata, and Lima cardii- 
formis occur throughout the whole series of beds, but are especially 
abundant at certain levels in the series marked D. In a lenticular 
sandy layer, about the middle of Group D, we found the following :— 
Grovp D. 
Lithodomus sp. | Rhynchoneiia obsoleta, Sow. 
Lima cardiiformis, Sow. | Terebellaria ramosissima, Lamx. 
Trichites nodosus, Lye. | Cidaris sp. 
Pecten vagans, Sow. Acrosalenia sp. 
Terebratula maxillata, Sow. Cladophyllia sy. 
Waldheimia (Eudesia) cardium, Lam. | Peronidella sp. 
From the sandy and clayey beds, marked E, and especially from 
the limestone-beds which are developed i in the sandy layer at certain 
points, we obtained the following fossils :— 
Group E. 
Belemnites sp. | Waldheimia (Ornithella) digona, Sow. 
Mytilus furcatus, Goldf. _ W. (Eudesia) cardium, Lam. 
Ostrea Sowerhyi, Lye. | Rhynchonella obsoleta, Sow. 
O. gregaria, Sow. (rare). Berenicea Archiaci, Gregory. 
Corbula sp. Cidaris aff. br adfor densis, Wr. 
Cucullea aff. concinna, Phil. | Tsastrea limitata, Lamx. 
Terebratula att. bradfordensis, Walker. | Cladophyllia Con ybeart (2) Hd. & H. 
Some 300 yards east of the tunnel-mouth, an extremely fossili- 
ferous horizon occurs, at the very top of Group F. Here, separated 
by a thin clay from the main mass of false-bedded limestones, 
is a sandy limestone crowded with fossils. This limestone and 
the clay beneath it pass laterally, when followed westward, into 
the uppermost beds of Group F. The clay must be regarded, 
therefore, as only another instance of the development of lenticular 
clay-bands, so characteristic of the series. 
The commonest fossils at this horizon are :— 
Grovp ¥. 
Avicula (Oxytoima) costata, Sow. (very | Rhynchonella obsoleta, Sow. 
abundant). Rh. concinna, Sow. 
Pecten lens, Sow. | Waldheimia (Ornithella) digona, Sow. 
P. vagans, Sow. Terebratula maxillata, Sow. 
Lima cardiiforimis, Sow., T. brad fordensis, Walker. 
and numerous lamellibranchs. 
(6G) Great Oolite (white oolite), Groups C to A. 
These consist of massive, fine-grained, white oolitic limestones 
which include non-persistent layers of fossiliferous clay and sand 
(B) near the top. 
The limestones are not highly fossiliferous, but the horizon B is 
marked by a very distinctive assemblage of fossils. | 
Terebratula maxillata and Rhynchonella obsoleta occur sparingly ; 
but the horizon is characterized by the abundance of casts of 
lamellibranchs. These belong to the genera Pholadomya, Pleuromya, 
Unicardium, and Cypricardia(?); the large casts of Pholadomya 
deltoidea may be almost said to form a continuous layer. 
There is a striking change in the faunal facies, as we pass 
