40O HISTORY OF GEOLOGY AND PAL/EONTOLOGY. 



series of monographs on the British Fossil Brachiopods 

 begins with a masterly exposition of the organisation of living 

 Brachiopods. For this introductory chapter Owen had 

 undertaken the anatomy of living Brachiopod types, and 

 Carpenter the detailed structure of the shell. 



The whole series of the British Fossil Brachiopods was com- 

 pleted in 1870, the finished work being presented in the form of 

 three handsome volumes published by the Palaeontographical 

 Society; the illustrations were drawn by the author himself. 

 Three supplementary volumes were added between 1873 and 

 1885, and finally Davidson contributed a review of the living 

 Brachiopods and an exhaustive bibliography of the whole group. 

 Davidson's work brought the knowledge of fossil Brachiopods 

 to a higher standpoint of excellence than had been reached by 

 the palaeontological knowledge of any other group of Inverte- 

 brates. His classificatory system has continued as the standard 

 of all subsequent research. 



At the present day the number of palaeontologists and strati- 

 graphers who interest themselves in fossil Brachiopods is so 

 large that it is quite impossible to attempt to mention here 

 the more recent widely-scattered literature. It will suffice to 

 indicate the leading tendency in the newer works. Whereas 

 Davidson in his systematic treatment allowed for a considerable 

 extent of variability in his definitions of genera and species, the 

 new direction of research guided by Hall, Clarke, Beecher in 

 North America, 'and by Waagen and Bittner in Europe, 

 tries to restrict generic and specific definitions within the 

 narrowest possible limits, in order to enhance the value of 

 fossil Brachiopods for the characterisation of stratigraphical 

 horizons. A systematic review of all known Brachiopods forms 

 an introductory chapter in the comprehensive monograph of 

 Palaeozoic types which has been published by Hall and 

 Clarke. The number of genera has been greatly increased, 

 and in many cases species have been elevated to the rank of 

 genera. A new classification was proposed in 1889 by Beecher, 

 in which it has been the author's aim to bring the ontogenetic 

 and phylogenetic development of the group into more apparent 

 correspondence, and to apply the differences in the beak region 

 more often for systematic distinctions. 



Mollusca. Palaeontology has taken no small share in 

 building up a knowledge of conchology. The study of the 



