ioo SCIENCE PROGRESS. 



neous rock and radiolarian chert has recently been detected 

 in the Ordovician rocks of the southern uplands of Scotland. 

 Jasper is associated with so-called spheroidal basalt in Cali- 

 fornia, and Mr. Teall thinks that this jasper may possibly 

 be a radiolarian deposit. He remarks that it seems "almost 

 impossible to avoid the conclusion that the peculiar struc- 

 tures in question are in some way connected with the 

 physical conditions under which the cherts accumulated," 

 and asks if they may not be characteristic of submarine and 

 possibly deep-sea lavas. Anything tending to throw light 

 on the remarkably interesting palaeozoic radiolarian deposits, 

 which have been so largely detected of late years, is of in- 

 terest, but it may be doubted whether it is not yet too early to 

 generalise on the connection between radiolarian cherts and 

 spheroidal basic rocks. The writer of this article finds in his 

 note-books observations of spheroidal diabases in Bohemia 

 in rocks of Precambrian, Ordovician, Silurian (Llandovery, 

 Wenlock and Ludlow) and Devonian ages. In most cases 

 they have broken along shales, and the association of radio 

 larian cherts with soft graptolitic shales may account in 

 some cases for the existence of the igneous rocks also in that 

 position, for some at any rate of these Bohemian diabases 

 are undoubtedly intrusive. 



In a stratigraphical paper (8) on the Skiddaw slates 

 of the North of England, the writer takes advantage of 

 the observations of Harkness, Nicholson, Ward, Goodchild, 

 Postlethwaite and others to summarise our present know- 

 ledge of these rocks ; he considers that the Skiddaw slate 

 group may consist of a thin series of Arenig rocks interfolded 

 with older ones. He gives a list of graptolites compiled 

 from previous lists with additions, and maintains that the 

 presence of Bryographis proves the existence of Tremadoc 

 beds in the Skiddaw district. The paper also contains 

 an attempt to subdivide the Arenig rocks of the Lake dis- 

 trict and adjoining regions. A paper by Mr. Reed (9) 

 contains a careful description of a new species of Phacops 

 of the sub-genus Chasmops (P. Marrt), from the Apple- 

 thwaite division of the Coniston limestone of Applethwaite 

 Common near Windermere. It is compared with other 



