142 FIELD GEOLOGY. 



tolerably hard and strong, and need little care beyond 

 the protective power of old newspapers. 



The character of the rock and its stratigraphical 

 position are almost sufficient to prove that it be- 

 longs to the lower part of the Magnesian limestone, 

 and the fossils abundantly confirm this surmise, being 

 those which are characteristic of the second member of 

 this series, the " fossiliferous limestone" of Prof. King. 

 Among them are, Fenestella retiformis, Producta Jior- 

 rida, Gamarophoria crumena, Monotis speluncaria, 

 Sckizodus obscurus, and Bakevellia antiqua. 



Eound the mouth of the coal-mine there are scattered 

 portions of the various measures passed through in 

 sinking the shaft; among the fragments of sandstone 

 and fireclay thus brought to light we may find remains 

 of Calamites, Stigmaria, and Sigillaria ; in the shales 

 and shaly sandstones we detect impressions of Lepi- 

 dodendron stems, together with the broken fronds of 

 Neuropteris, Sphenopteris, and other ferns, all black 

 and carbonized. 



In the dark shales also Unio-like shells occur, belong- 

 ing to the genera Anthracosia and Anthracoptera, but 

 they are often more or less crushed ; the best specimens 

 are obtained from the dark-grey ironstone nodules which 

 are scattered about, and which we ascertain to have been 

 derived from the shales below the first coal-seam (see 

 section on p. 212). Besides the bivalve shells, these 

 nodules contain beautiful fragments of fern leaves, as 

 well as Lepidostrobi, or the cones of the Lepidoden- 

 dron, and sometimes the scales or coprolites of fish ; it 

 was indeed the decomposition of the animal or vegetable 

 matter that determined their formation. 



