278 



illustrations, though somewhat rough, are on the whole good and 

 sufficient for their purpose. Among the least satisfactory are 

 the figures of Lagena marginata^ W. & B. (Plate X., Fig. F, 

 which would pass equally well for Biloculhia depressa d'Orb. var. 

 murrhyna^ Schwager) and of Pohjtrenia miiiiaceuni, Linne (Plate 

 XIT. Fig. Q.) 



More exception may be taken to some of the types selected by 

 the author. In such a book it would have seemed desirable that 

 the types selected should, as far as possible, belong to species of 

 abundant and wide-spiead distribution. ,This is not always 

 the case. Thus the two examples selected in illustration of the 

 cosmopolitan genus Hcqjlophragmium are both fossil forms, and of 

 restricted distribution even as fossils. The genus Cassidulina, 

 again, is illustrated, by a species (C. ccdahra, Seguenza) which is of 

 extremely rare and local distribution in both the recent and fossil 

 states. 



The final section of the book is devoted to a leview of the 

 geological history of the group, which has been largely extended 

 of late years, and to a considerable extent by the researches of 

 Mr. Chapman himself. The theory that the earliest forams were 

 of an arenaceous type has, like so many other theories, found no 

 confirmation in the geological record ; for the earliest known 

 arenaceous forms date no farther back than the Silurian (Wenlock 

 Series), while various Lower Cambrian rocks have yielded repre- 

 sentatives of no less than four out of the six families of perforate 

 Foraminifera, all of genera existing at the present day. The 

 group may therefore be regarded as firmly established even at 

 that early period. What the ancestors of these ancient though 

 varied tyj^es may have been we shall probably never know. 

 Probably the author's surmise is correct, that they are the 

 descendants of unknown forms, which being either wholly devoid 

 of a shell, or having only a thin chitinous investment, have 

 escaped fossilisation. 



The volume concludes with an excellent chapter on methods of 

 collection and preparation, and with a selected bibliography of 

 nearly two hundred of the most valuable books and papers 

 dealing with the group. A. E. 



Jonrn. qiuhtt Microscopical Club, &,-. 2, Vol. VIII., So. 50, April 1902. 



