566 Reviews — The Sub-Crag Detritus-Bed. 



Univalves, by Mr. S. Y. Wood. In the intervening years no fewer 

 than sixty-seven large quarto volumes, rich in illustrations, have gone 

 forth, each containing parts of numerous important monographs, but 

 until the appearance of the sixty-eighth volume the publication of 

 only one author's work has never been repeated. It is a sign of the 

 times, indeed, when this single part represents the total issue of the 

 past year's labours. 



The present instalment of this valuable Supplement to Mr. S. V. 

 Wood's Crag Mollusca continues the tale of the first part (noticed in 

 the Geological Magazine, 1914, p. 227) and deals with the difficult 

 group of the Pleurotomidse. 



Since the author, as he explains in his preface, has "followed, 

 more or less nearly, for the convenience of students, the arrangement 

 of the Marine Mollusca adopted by him [S. V. Wood] ", the new 

 Supplement to the very much earlier monograph, while adding 

 greatly to the value of Mr. Wood's work, will not, we fear, satisfy 

 entirely the more exacting and critical systematists of to-day, despite 

 the manifest care and pains bestowed upon it. No captious criticism, 

 however, can be applied to the plates, which are far and away the 

 best molluscan illustrations the Society has ever published, and 

 impress one at once as being really like the objects they represent, so 

 that altogether the student cannot fail to recognize the forms dealt 

 with, whilst the introduction of figures of recent species for 

 comparison with the fossil forms is a wise and very helpful course, 

 and cannot be too strongly commended to biologists in other groups, 

 whose labours enrich this Society's publications from year to year. 



II. — A Description of the Sub-Crag Detritus-Bed. By A. Bell. 

 Proceedings of the Prehistoric Society of East Anglia, vol. ii, 

 pp. 139-48. 



fPHE pursuit of the ignis fatuus of pre-Crag Man has not been 

 L without some useful results for the palaeontologist, since the 

 recent borings have enabled the author of this note to bring together 

 a most useful summary of the latest facts concerning the sub-Crag 

 detritus-bed. 



This bed, first brought to the notice of geologists by Professor 

 J. S. Henslow in 1843, is made up of the following constituents : 

 (1) Phosphatic nodules (the so-called Coprolites), (2) sandstone 

 nodules or box-stones, (3) rocks of various, ages earlier than the 

 Crag, (4) large chalk flints, many unrolled, (5) rolled and water- 

 worn bones, usually much mineralized, (6) Cetacean beaks (rostra), 

 and other bones, (7) bones and teeth of land mammalia, (8) wood and 

 other items, chiefly of uncertain age. These groups belong to very 

 different periods and are not of equal value numerically. The 

 phosphatic nodules have yielded some twenty species of Chelonia, 

 Pisces, and Crustacea, all of Sheppey types. The box-stones, the 

 author considers, present in their fauna hardly any elements in 

 common with the Diestian, to which they have been referred. The 

 list of fossils contains eighty species of the more characteristic shells 

 of the Oligocenes of North Germany, Belgium, and Denmark, but the 



