264 MESSRS. G. W. LAMPLTTOH AND J. F. WALKER ON [May I903, 



Summary. 



1. This paper describes a newly-discovered fossiliferous band at 

 the top of the Lower Greensand, overlain by the Gault, in the 

 sand-pits at Shenley Hill, near Leighton Buzzard (Bedfordshire). 



2. The fossils of this band present a facies different from that of 

 any previously-known fossiliferous horizon of the Lower Greensand, 

 and show closer affinities with the fauna of the Upper Greensand 

 than have hitherto been recognized in any deposit below the Gault. 

 The brachiopods are closely allied to those contained in the Tourtia 

 of Belgium. 



3. The fossiliferous bed is rather sharply marked off from the 

 underlying unfossiliferous ' silver-sands,' but is still more sharply 

 marked off from the overlying Gault. Stratigraphically it forms 

 part of the Lower Greensand, and cannot, without violence to the 

 accepted classification of the deposits, be considered to belong to 

 the Gault. 



4. The fossils constitute a newer Lower Cretaceous fauna than 

 has yet been recognized as such in England. Several species, hitherto 

 supposed to be confined to the Selbornian, are now shown to have 

 been in existence before the deposition of the Gault. 



5. The lithological characters of the bed indicate a sea-bottom of 

 moderate depth, swept by powerful currents ; and the conditions 

 were thus similar to those which persisted in the neighbourhood 

 throughout Lower-Greensand times. The overlying Gault shows a 

 change to more tranquil waters, probably of greater depth. 



6. The brachiopoda, which are the most abundant fossils, are 

 fully described, and representative specimens figured. These include 

 several species or well-marked varieties regarded as new, together 

 with others not hitherto recorded in England. 



EXPLANATION OF PLATES XVI-XVIII. 



[All the specimens are figured of the natural size, except where otherwise 

 stated. The}' have been presented by the Authors to the Museum of the 

 Geological Society of London. 1 



Plate XVI. 



Figs. 1 a, 16, & lc. Terebratulu capillata, d'Archiac. This Shenley specimen 

 agrees with d'Archiac's type. 

 2 a & 2b. Terebratula capillata, d'Archiac. A specimen with a wide fold. 

 Sa&i3l). Terebratula capillata, d'Archiac. A smaller specimen, with a 

 wide fold. 



4 a, 4 A, & 4 c. Terebratula capillata, d'Archiac. An ovoid globose specimen. 



5 a k 5b. Terebratula capillata, d'Archiac. A young specimen. 

 Fig. 6. Terebratula capillata. d'Archiac. A very young specimen. 



Figs. 7 a, 7 b, & 7 c. Terebratula biplicata, tar. gigaiitca, nobis. This is the 

 largest specimen that we have obtained from Shenley. 



Plate XVII. 



Figs. 1 a & 1 b. Terebratula biplicata, var. Dutempleana, d'Orb. 



2 a & 2 b. Terebratula deprcssa, var. shenleyensis, nobis. 



3 a & 3 b. Terebratula deprcssa, var. slienleyensis. A smaller specimen. 



4 a & 4 b. Terebratula Moutoniava. d'Orbigny, var. 



