OP THE CARBONIFEROUS STRATA. 



191 



so much, but have a straighter course. The upper or relief 

 side of the trail is marked with transverse striae, veith a slight 

 ridge in the centre ; the concave side is rather flat, and has a 

 ridge in the middle. The exact position of this flag in the 

 carboniferous strata, I am unable at present to give. 



In the beds of flags found in the lower division of the 

 Lancashire coal field, are some sinj^ular markings which have 

 not yet been much investigated. They occur both in the 

 upper and lower beds, namely, the Old Lawrence and the 

 Haslingden flags, and are evidently of different origin. 



In the upper bed of flagstones, much used in this neigh- 

 bourhood for in-door floors, and having very smooth faces, 

 arc often seen numerous indentations, passing through several 

 laminas of stone. These shew an orifice on their upper and 

 a projection on their under surface. An example of these 

 marks is figured in the paper by the author, printed in vol. 

 viii. (new series) of the Transactions of the Society, at p. 170. 

 They are very common both on the Lancashire, Cheshire, and 

 Yorkshire flags of the upper series, but little, if any, atten- 

 tion has been hitherto directed to inquire into their origin, 

 and in my former paper no allusion was made as to the animal 

 which had caused them. 



During the formation of the tunnel on the Bury and Liver- 

 pool railway at Upholland, in the upper flags there I collected 

 some of the stones, having very distinct markings on their 

 surfaces, and upon breaking them crossways, obtained evi- 

 dence as to the probable cause of the holes in these flags at 

 least, if not of those found in other places. But it is likely 

 that other specimens from different localities, if carefully 

 examined, will afford similar evidence. The upper part of 

 the holes in the larger specimens is about eight-tenths of an 

 inch in diameter, and gradually tapers to a depth of nine- 

 tenths, and then, by a curved orifice of two-tenths of an inch, 

 is connected with another conical hole like the first. These 

 holes, a good example of which is shewn in fig. ^, plate 1, 



