1849.] SHARPE ON THE SECONDARY ROCKS OF PORTUGAL. 153 



miles, the beds are crossed in a descending order : their dip is gene- 

 rally to the S.W. at angles rarely exceeding 10°, but there are also 

 some minor disturbances which spread them over a greater breadth 

 of country than they would otherwise cover : the axis of elevation 

 passes near Refugidos, beyond which spot the section re-crosses the 

 same beds with a contrary dip in an ascending order. The following 

 is the series seen in the first half of the section. 



Between Tojal and Bucellas the ferruginous sands and sandstones 

 of the subcretaceous series are seen overlaid by the hippurite lime- 

 stone which there dips S.S.W. 15°: near Bucellas these sands dip 

 S.W. 10°, and contain some unimportant beds of limestone : they 

 closely resemble the upper division of the subcretaceous sands seen 

 on the west of Lisbon, and appear to lie conformably under the hip- 

 purite limestone ; yet it is probable that this is deceptive, since the 

 beds below these next to be described belong to a very low portion of 

 the subcretaceous series, and differ from all those seen between Lisbon 

 and the coast : therefore there must be a break in the continuity of 

 the series, either between the hippurite limestone and the ferruginous 

 sands of Bucellas, or between these and the calcareous series below 

 them ; and the former is far more probable. 



After passing Bucellas the section crosses lower beds of sand and 

 marl with some alternations of limestone. Below these are beds of 

 argillaceous limestone containing some corals, alternating with marl : 

 these pass downwards into a series of beds of grey limestone of con- 

 siderable thickness, and so full of corals as to suggest the idea that 

 they were originally part of a great coral reef : at Trancozo de cima 

 on the line of our section their dip is S.W. 20° : these limestone beds 

 are one of the principal features in the geography of this district, as 

 they form the crest of the steep ridge of hills extending to the N.W. 

 from the south side of Alhandra towards Sobral, on which were the 

 principal defences of the lines of Torres Vedras. 



Below the preceding are seen alteraations of sand and sandstone 

 with some beds of coralliferous limestone overlying a great thickness 

 of ferruginous sands which cover a large space of flattish country near 

 Aruda, and in which there are also some beds of sandstone, marl and 

 limestone. 



Below this arenaceous series lies a coarse white limestone which 

 forms a saddle at Refugidos, and which is the lowest bed exposed on 

 this line of section, and the lowest member of the subcretaceous series 

 observed in Portugal. Yet from the irregular positions in which the 

 beds of this series rest on the Jurassic limestones, we cannot judge 

 whether we have here really reached the bottom of the subcretaceous 

 series. 



I received a rich collection of fossils, through the kindness of Senor 

 Edwardo Augusto Boaventura, from the limestone beds lying beyond 

 Sobral towards Torres Vedras, which I believe to be the continuation 

 of those seen on the last section at Trancozo de cima : it contains the 

 following species, viz. : — 



Cidaris clunifera, Agassiz. Nerinsea turbinata, n. s. 



Natic a prselonga, Deshayes. Artemis cordata, n. s. 



