288 



THE SIGNIFICANCE OF DOMINANT EUADENIATE 

 HELICES IN AFRICA. 



By J. W. TAYLOR, M.Sc. 



("Read before the Society, March ist, 1922). 



Plate X. 



The recent issue of a volume dealing with the Malacological results 

 of the Congo Expedition, 1 909-1 91 6, organized by the American 

 Museum of New York, calls for the special congratulation of the 

 scientific world, not only on account of the really superb manner in 

 which the work has been produced, but also, that the study of the 

 molluscan material was so happily placed in the supremely capable 

 hands of Dr. Pilsbry, resulting in large and important additions and 

 corrections to our knowledge of Central African life, securely 

 based upon the detailed examination and study of the animal 

 organization. 



The present volume deals exclusively with the land mollusca and 

 embraces 370 pages of text and 23 plain and coloured plates, in 

 addition to the 163 figures or maps in the text, illustrating the dis- 

 tribution and internal organization of the animals, as well as the 

 morphological peculiarities of the shells. 



More than 6,000 specimens were examined or dissected for the 

 purpose of the present work, the 160 new species, subspecies and 

 'mutations, necessitating, from their unusual novelty, the institution of 

 29 new genera, subgenera and sections for their reception. 



The whole collection represents 214 species and subspecies and 

 brings up the known total of Belgian Congo snails to about 400 kinds. 



Perhaps one of the most important results of the study of this great 

 mass of material has been its influence upon our knowledge of the 

 Helicidian groups and the geographical problems connected therewith, 

 demonstrated by the fact that the predominant group of Helicids in 

 the region investigated is proved to be Euadeniates of East Asiatic 

 type, the nearest known, though remote allies being the Japanese 

 genera Trishoplita and Eulotella, which are, however, specialized in a 

 different way.. 



Prof. Pilsbry's classical hypothesiis that there have been five chief 

 periods or waves in the development of Helicidian life, separated 



