142 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 6, 



through ; but it does not disturb the carboniferous beds which must 

 be posterior to its eruption*. 



Tipper Division of the Silurian Formation {Upper Silurian). — 

 This consists of beds of light blue shale and argillaceous schists con- 

 taining none of the species found in the beds below, but characterized 

 by Cardiola interrupta, and some other bivalves, Orthocerata, Grap- 

 tolites, &c., all flattened and distorted. These beds extend along the 

 western edge of the Silurian district from Ponte de Matta to Sazes, 

 and are seen to pass below the carboniferous beds between Passo 

 and Portela de Loredo. We may conclude from their organic re- 

 mains, that the beds belong to the age of the Wenlock formation of 

 England f. 



Sa7i Pedi'o de Cova near Fallongo. — An examination of the beds 

 of that locality confirms the view taken by Mr. SharpeJ, that the 

 Carboniferous series, there worked for coal, is at the base of the Silu- 

 rian system, and that the position of the Coal below the Silurian 

 slates containing Trilobites, Orthis, &c., cannot be explamed by a 

 supposed inversion of the whole series of beds. 



Argillaceous and CrtjstalUne Schists. — There are two schistose 

 formations in the neighbourhood of Bussaco, below the Silurian se- 

 ries. The upper of these, which may be called Cmnhrian, is an ex- 

 tensive series of unfossiliferous beds consisting principally of argilla- 

 ceous schists with some grits ; their position is marked on the map 

 forming the eastern boundary of the fossiliferous region described in 

 this memoir, and also partially bounding on the west the Silurian 

 ridge of Bussaco. To the same series may probably be referred the 

 schists of Estorreja, Ovar, &c. §, and the lowest beds seen at San 

 Pedro de Cova. 



Besides the above there are two small districts of mica schist and 

 chloritic schist which are shown on the map and sections ; one be- 

 tween the northern end of the Serra de Bussaco and Villa Nova de 

 Monsarres ; the other a little west of that Serra, near Botao. 



On the left bank of the Douro below Jeramunde, rising from the 



* Organic Remains of the upper division of the Lower Silurian beds : — 



Phacops Dujardini, Rouault, Bull. Porambonites lima, n. s. 



Soc. Geol. Fr. iv. t. 3. f. 5. Leptfena Beirensis, n. s. 



Dithyrocaris ? longicauda, n. s. ignava, n. s. 



Orthis exornata, n. s. deltoidea, Conrad, sp., Hall, 



Bussacensis, n. s. Pal. N. York, t. 31 a. f. 3. 



Mundse, n. s. Pleurotomaria Bussacensis, n. s. 



testudinaria, Dalm. Favosites fibrosa, Goldf. 



Berthoisi, Rouault, Bull. Soc. Synocladia Lusitanica, n. s. 



Geol. Fr. vi. t. 2. f. 4. hypnoides, n. s. 



parva. Pander. Disteichia reticulata, n. s. 



Porambonites Ribeiro, n. s. Retepora, 1 or 2 species. 



t Organic Remains of the upper division of Silurian Rocks : — 

 Graptolithus Ludensis, Sil. Syst. Orthoceras, 4 species. 



t. 26. f. 1. Cardiola interrupta, Sil. Syst. t. 8. f. 5. 



Creseis, 1 species. Cardium striatum? Sil. Syst. t. 6. f. 2. 



X See Journ. of Geol. Soc. vol. v. p. 145-148. 



§ See Joum. of Geol. Soc. vol. v. pp. 149 & 150. 



