1848.] SHARPE ON THE GEOLOGY OF OPORTO. 147 



Orthoceras remotum, Salter, MSS. 



, .1 fragment, 2^ inches in diameter. 



BelleropJwn Duriensis, n. s. 



Graptolithns Murchisoni ?, Sil. Syst. pi. 26. fig. 4. 



Besides the above, I saw many shells and trilobites too imperfect 

 to be determined ; the fragments of trilobites are very abundant, and 

 many of them are remarkable for their size ; one crushed specimen 

 measures seven inches across the body. Many impressions of the 

 tails of trilobites were seen between six and nine inches across, but 

 all much distorted. 



Mr. Salter has had the kindness to assist me in determining the 

 species of the trilobites ; and Mr. Morris has helped to fix the spe- 

 cific characters of the shells. 



4. Carboniferous series of San Pedro de Cova : this series of beds 

 lies conformably under the slate series just described, and the passage 

 from the one set of beds to the other is gradual ; the following are 

 the details, viz. : — 



a. Red sandstone, dip E.N.E. \ N. 45° ; several hundred feet thick, 

 with alternations of dark carbonaceous beds in the lower part. 



b. Coarse conglomerates of different characters alternating with 

 black carbonaceous shales : some of the conglomerates are quartzose 

 and micaceous, others grey with a good deal of carbon ; the whole 

 many hundred feet thick*. 



c. Coal ; about six feet thick. 



d. Coarse micaceous conglomerate alternating with black carbo- 

 naceous shale. 



e. Coal ; too thin to be worked. 



f. Coarse carbonaceous conglomerate. 



g. Coal ; four beds from two to five feet thick, varying in thick- 

 ness in different spots, and separated by three or four feet of black 

 shale. These beds are all worked from the same galleries, and 

 furnish at present the principal supply of coal. They rest on black 

 shale. 



h. Shales containing chlorite, resembling in colour the chloritic 

 schists on which they rest, and from the debris of which they have 

 evidently been formed. 



The carbonaceous series No. 4 is probably between 1000 and 



* Both in the shales and sandstones impressions of vegetable remains are found, 

 but usually in bad preservation. Mr. Charles J. F. Bunbury has had the kindness 

 to examine the specimens, and finds in them " indications of three species of ferns, 

 all in bad preservation and very indistinct; the best-preserved specimen is in fruc- 

 tification, and seems to have a strong resemblance to Pecopteris Cyathea, ^hxch. is 

 a common fern of the coal-measures. Another is extremely indistinct, but reminds 

 us in some degree of Pecopteris muricata. The third resembles Neuropteris 

 tenuifolia in the form of its leaflets ; but the total obliteration of the veins makes 

 it impossible to pronounce upon it with any approach to confidence." It thus 

 appears from the note with which Mr. Bunbury has favoured me, that there are in 

 the carboniferous beds at Vallongo several ferns with strong resemblance to certain 

 species known in the coal-measures. Now that attention has been drawn to a cir- 

 cumstance of so much interest, it is to be expected that before long specimens may 

 be brought to hght which will show whether the same species of plant existed at 

 two periods so remote from one another. 



