POPDLAE GEOLOfiT. 



85 



The occurrence o£ these Anthracosia and Cardina, the former 

 brackishwater-shells and the latter marine-shells, especially when taken 

 along with the character o£ the fish remains, indicate that the secoal strata 

 were deposited in some vast estuary or brackishwater sea similar to the 

 Baltic or Black sea. It is a well-known fact amongst naturalists, that 

 marine and freshwater fish are often found living together in these neutral 

 grounds as we may term them. In the Baltic sea for instance, which is 

 only about one-third as salt as ordinary sea- water, the common river perch 

 (perca fluviatilis) was caught last summer, along with a number of 

 undoubted marine fish, which consisted of the pipe-fish, blenny, prawns, &c.* 

 Knowing this fact then, we need not be surprised to find both marine 

 and freshAvater animals in our coal strata, which from the character of 

 their vegetable remains are believed by our best geologists to have been 

 deposited in wide estuaries or braclcishwater seas. 



But to return to the Coal-pit. After searching amongst the ironstone 

 a few minutes : I f oimd a fine specimen of Sigillaria Pachyderma which I 

 •wrapped up and "bagged" I passed over a number of fragments of 

 Ulodendra, Calamites, and Lepidodendra as I had got better specimens at 

 home. I also found some very fine specimens of " Unios. " They lay 

 softly embedded in slabs of shale, both singly and in groups of about haK 

 a dozen and better specimens I never met with, so selecting one of the 

 smaller slabs I carefully broke away the imnecessary shale, so as to reduce 

 it to a convenient size for my bag. It is always best to reduce the speci- 

 mens to the size best suited for the cabinet while you are on the spot, 

 where fresh ones may be had in case of accident. The smaller species of 

 "Unios" were also very plentiful, in these shales. I had not been engaged 

 here very long, ere a shower of rain fell, but happily it soon cleared up and 

 the rest of the day proved fine. Not being able to meet with anything 

 more here, I pursued my journey still keeping to the east, until I had got 

 fairly into the midst of the Low-moor collieries. As far as the eye can see 

 on every side coal-pits are visible. Not a picturesque nook, meadow or 

 hill-side but is occupied by tall chimneys and engine-houses and surrounded 

 by acres of the "black-mineral." 



The country about here, is a complete network of railways, stretcliing 

 away for miles on either hand The main line runs from Wibsey Slack 

 to the f lu-naces at Low-moor and from thence doAvn to Brighouse. The 



• See a paper on this subject by Jlr. Alfi'cd Lloyd, in Science, Gossip, July 1, 1866. 



