1849.] SHARPE ON THE SECONDARY ROCKS OF PORTUGAL. 163 



Limestone of Montem6r-velho, ^c. 



The town of Montemdr-velho, on the north bank of the Mondego, 

 twelve or fifteen miles below Coimbra, stands on the southern extre- 

 mity of a ridge of limestone about a mile wide running to the N.N.E., 

 which is raised unconformably at a high inclination through the sub- 

 cretaceous sandstone district (see section No. 2, fig. 3). At Montemor 

 the limestone beds form a steep anticlinal axis ; but this is merely local, 

 as a little north of the town they all dip S.E. 30°, and further to the 

 north E. 30°. The ridge is of moderate height and dies away gra- 

 dually in its course northward. 



The limestone is rather soft, white, and very argillaceous ; it contains 

 abundance of Ammonites, Belemnites, and other shells which prove it 

 to be of the age of the lias : the following is the list : — 



Gryphsea obliquata, Sow. Ammonites catenatus, Sow. 



Plicatula spinosa, Sow. ■ spinatus, Bruguiere. 



Terebratula bidens, Phillips. Stokesii, Sow. 



ornithocephala, Sow. Thouarensis ?, D'Orb. 



punctata, Sow. Belemnites paxillosus, Schlotheim 



tetrahedra, Sovj. Nautilus truncatus, Sow 



Ammonites brevispina ?, Sow. Turrilites Beirensis, n. s. 

 Braunianus ?, D'Orb. 



I only followed the limestone for four miles to the northward of 

 Montemor, but in crossing from Aveiro to Coimbra, I observed a 

 limestone of precisely similar mineral character at Vendas Novas, four 

 leagues north-west of Coimbra : this place is about twenty miles 

 N.N.E. of Montemor, and is consequently on the exact strike of the 

 Montemor limestone ; several fossil shells are common to the two lo- 

 calities, and the list of those found at Vendas Novas connects the 

 limestone of that place with the lias. I feel convinced therefore that 

 this is the northern prolongation of the Montemor ridge of limestone. 



The following species were found at Vendas Novas : — 



Plicatula spinosa, Sow. Ammonites spinatus, Bruguiere. 



Spirifer Beirensis, n. s. Stokesii, Sow. 



granulosus, Goldf. Belemnites exilis, D'Ori. 



Terebratula tetrahedra, Sow. paxillosus, Schlotheim. 



carinata, Lam. 



The beds at Vendas Novas dip S.E. 10°, and rise very little above 

 the level of the surrounding subcretaceous beds, with which they 

 might easily be confounded, if the organic remains were not carefully 

 observed. Their position is shown in section No. 1 (fig. 2). 



The prolongation of the line of the limestone to the N.N.E. would 

 bring it across the road from Coimbra to Oporto near Agueda, but as 

 I saw no trace of such limestone in that neighbourhood, I presume 

 that beyond Vendas Novas it sinks below the subcretaceous beds. 



There is however a patch of similar limestone at Mealhada on the 

 Oporto road, about three leagues north of Coimbra : its characters are 

 exactly similar to those of the limestones of Montemor and Vendas 

 Novas, and like them it contains the Belemnites paxillosus in abun- 

 dance, so that it is doubtlessly part of the same bed, though on a dif- 

 ferent hne of strike. 



