THE TRENTHAM GRAVEL BEDS. 107 



Atrypa hemispherica, A. reticulatus var., Spirifer crispus and 

 trapezoidalis, Strophomena depressa, S. compressa, S. pecten, 

 Pterinea demissa, Euomphalus sculptus, Orthis elegantula, 

 Holopea sp., Holopella absoleta, Palasocyclus pra3acutus, 

 Halysites catenulatus, Petraria subduplicata, P. creuulata var., 

 Phacops Weaver!, Tentaculites Anglicus. The Mountain Lime- 

 tone series consist of Poteriocrinus crassus and other species, 

 Rhodocrinus sp., Actinocrinus sp., Platycrinus sp., Lithostro- 

 tion irregulare, L. Martini, Michelinia megastoma, Zaphrentis 

 sp., syringopora reticulata, Fenestella plebeia, Phillipsia sp., 

 producta semireticulata, P. concinna, P. mesoloba (?), Steptor- 

 hyncus crenistria, Spirifer triangularis, S. bisulcatus, S. octopli- 

 catus, S. glaber (?), Chonotes variolata, C. Hardrensis, Dentali- 

 um ingens. Of the latter series of fossils encrinital stems are 

 by far the most numerous, and the matrix in which these 

 are enclosed, in fact nearly the whole of the fragments of 

 Carboniferous limestone containing fossils, whether by being 

 subjected to great heat, or by some chemical process, are 

 soft and white, and easy of disintegration. In a similar 

 condition we find numerous agates, the thin blanched laminas 

 falling off to the touch in a remarkably interesting and 

 suggestive manner. More interesting, however, and more 

 remarkable still are the curious spots with which we see 

 almost every pebble, whatever its size, if of a sufficient 

 degree of hardness, more or less covered. In fact these 

 spots are unmistakably characteristic of the Bunter gravels 

 over the whole area of their occurrence. I have never 

 noticed them in any other gravels, nor are they retained 

 by individual pebbles which by denudation become, as they 

 very largely do, mixed up with and enter into the com- 

 position of drift and valley gravels of more recent age. 

 I do not know if the presence of these spots has been 

 satisfactorily accounted for, but if we, as we may dp in 

 this particular quarry, examine thousands upon thousands 



