146 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 29, 



at a high angle ; the lower beds dip in that direction 60°. This 

 series is of great thickness, 



2. Black carbonaceous slate lying conformably below the micaceous 

 sandstone and alternating with dark clay-slate ; with the exception 

 of some local undulations the beds dip N.E. 60° to 70°, and the 

 cleavage of the beds of slate dips N.E. 70° to 80°. Among the 

 shales are numerous beds three to six inches thick of indurated fer- 

 ruginous clay passing into clay iron-stone. The appearance of these 

 carbonaceous shales accompanied by clay iron-stone is exactly that of 

 the shales of our coal-fields. Several small trials have been made for 

 coal among the black shales, but none has been found. This series 

 is of considerable thickness. 



3. Clay-slate, usually dark grey or black, and hard, but occasion- 

 ally soft, chloritic, and of a pink or yellow colour. The upper beds 

 of slate lie conformably under the carbonaceous shale, dipping N.E. 

 60°, with a cleavage which dips N.E. 80° ; a little farther westward 

 the same beds dip W. 30° S. 25°, the cleavage dipping AV. 30° S. 65°; 

 this dip continues to Ponte Ferreira, west of which the slates regain 

 their usual direction, dipping S.E. 45°, and the cleavage S.W. 80°. 

 About 1^ mile east of Vallongo the cleavage is perpendicular with 

 a strike of N. 30° W., which is the mean direction of the strike of 

 the beds and cleavage-planes : the slate at this spot is of a light 

 colour and contains chlorite. Thence to Vallongo is a hard dark 

 roofing-slate of the finest quality, dip N.E. 45°, dip of the cleavage 

 N.E. 60° to 70°. These slates are extensively quarried near Vallongo 

 for slabs and flags, but have not yet been applied to roofing, which 

 throughout Portugal is made of tiles. The lowest beds of this series 

 are soft, of light colours and chloritic. The thickness of the slate 

 series must be very considerable, but owing to several undulations of 

 the beds it is difficult to estimate it. The lower beds of the dark 

 grey slate, and all the beds of the lighter soft slates at the base of 

 the series, are rich in organic remains, which I collected to the north, 

 south, and west of Vallongo ; but I found none to the eastward of 

 that village, nor in any of the beds above the fine roofing-slate. Most 

 of these fossils are of new species, but they are all of forms common 

 in the Lower Silurian rocks of the north of Europe, and all the known 

 species among them belong to the Lower Silurian formation. 



The following species were found : — 

 Calymene Tristani, Brongniart, Tril. pi. 1. fig. 2. 



, another species ; specimens imperfect. 



Ogygia Guettardi, Brojigniart, Tril. pi. 3. fig. 1. 

 Isotelus Powisii, Portlock, Londond. pi. 6. fig. 1. 

 Illcenus Lusit aniens f n. s. 



Chirui'us ; fragments of an undescribed species. 

 Beyrichia or Cy there ; a small species, abundant. 

 Orthis Noctilio, n. s. 



Miniensis, n. s. 



Duriensis, n. s. 



Lusitanica, n. s. 



, fragments of several other species. 



