Notes and Comments. 371 



"" Algae " may be present ; when these bodies increase in 

 quantities the type passes into the one following. (3) Bog- 

 heads.— Here very pale-coloured " algae " form the principal 

 and sometimes almost exclusive constitutent, as in torbanite 

 and kerosene shale. A matrix like that of the cannels may 

 be present in varying amount, as also may spore-coats and 

 patches of " bituminous " material. Of these three types, 

 the first is so named by Potonie, while the second and third 

 form his sapropelic group.' 



THE INGLETON SLATES. 



Ill The Proceedings of the Geologists' Association (Vol. 

 XXVIII. , part 2), in a ' Note on the Correlation of the Ingleton 

 Slates,' Mr. J. F. N. Green considers ' that the Ingleton Slates 

 and Grits must go back into the Bala as the base of the Coniston 

 Limestone Series. They show that Borrowdale Volcanics, 

 with their associated acid intrusions, extended in force many 

 miles south of their present exposures. They give a glimpse 

 of the vast denudation undergone by that series in Ordovician 

 time.' He also doubts whether the thickness of 800 feet 

 assigned to the ' granite ' can be substantiated. It seemed to 

 him a mere shoal of no great size. Most of the quarry is in 

 mudstone and sandstone. 



STUDIES IN EDRIOASTEROIDEA. 



Readers of The Geological Magazine during the last fifteen 

 years will remember the various scholarly papers by Dr. F. 

 A. Bather dealing with certain complicated forms of Echino- 

 derms, many of which have been illustrated by admirable 

 plates. Dr. Bather has already earned the gratitude of 

 students of this difficult group by the careful and detailed 

 descriptions he has given of many of the forms. He has recently 

 still more assisted these workers, by reprinting under one 

 cover his various contributions, with the title of ' Studies in 

 Edrioasteroidea, I. -IX.' These are published by the author at 

 ' Fabo ' Marryat Road, Wimbledon, at the price of 10/-. The 

 book contains over 400 pages, has a preface and an index, 

 and there is no doubt it will be of considerable service in its 

 present form. The original pagination etc., of The Geological 

 Magazine has also been retained, so as to prevent confusion 

 in the way of references. Dr. Bather is the best English 

 authority we have on this subject, hence anything from his 

 pen is worthy of permanent preservation. We are glad to 

 notice that the work is thread sewn, and not stabbed through 

 by wire. 



SCIENCE PROGRESS 



Science Progress for October contains the usual summaries 

 of recent advances in Science, by specialists ; a number of 

 notes, essays and reviews ; as well as the following papers : — 



1917 Dec. 1. 



