62 PROP. T. G. BONNET ON THE ERRATIC [Feb. 1 896, 



nation of thin sections may lead to a generic or even a specific 

 determination. 

 Lignite (B). — A naked-eye examination of this smaller piece of 

 lignite brings out the features of coniferous wood. The annual 

 rings are fairly well marked. In thin slices the tracheids and 

 medullary rays are clearly seen, but the preservation is not 

 sufficiently good for one to recognize the manner of occurrence 

 of the bordered pits. In one slide there are a number of fungal 

 hyphse distinctly preserved, running irregularly through the 

 woody tissues. 

 The general impression arrived at from an examination of the 

 specimens is that the rocks are probably Mesozoic in age, and either 

 Jurassic or Wealden. But, without further evidence, it would be 

 rash to offer a more definite opinion as to the geological horizon/ 



Ice-worn Stones. 



These are all striated, and in form resemble the ice-worn specimens 

 from a till or boulder-clay. Though I have not used an acid, and 

 scarcely employed the knife, I think the following determinations 

 are correct. 



(2) A fine-grained dark grit, probably identical with (19). 



(9) A slate-grey limestone, apparently a piece of Carboniferous 



Limestone. 

 (18) A dark grey limestone, Carboniferous, or possibly Devonian, 



not unlike the matrix of (3). 

 (15) An almost black compact limestone (? traces of small organisms) ; 



very like some of the darker Carboniferous Limestone of 



Britain. 



(10) A heavy compact brown rock, probably a piece of ironstone 

 (? Carboniferous). 



In addition to the above-mentioned specimens are five glass 

 tubes, containing samples of the glacial deposits, described by 

 Col. Feilden ; in four cases clay, in the other sand. Small portions 

 of each have been studied under the microscope. In those from the 

 clay I have identified the folio wing minerals : — Fairly common : quartz 

 and felspar (plagioclase and microcline recognized); much more 

 sparingly, a colourless mica, hornblende and augite — both green- 

 coloured, garnet, zircon, iron oxides, and rounded grains of glau- 

 conite, some certainly the casts of foraminifera. 



The tube marked A was filled with lumps of a rather hard, dark, 

 brownish-grey clay, and in the preparations from it I also found a 

 sponge-spicule. B contained a mixture of a more earthy deposit, 

 nearly the same colour as the clay, with a little grey sand. Here I 

 identified the speckled filmy substance frequently seen in muds 

 and the colourless mica was more abundant. There was also a little 

 biotite and one or two sponge-spicules. C contained a material 

 like A, but a little darker in colour and not quite so coherent. 

 Here too was the filmy substance, as before ; also chlorite or a 

 greenish biotite, a sponge-spicule, and one possibly belonging to 



