2 STROPHOCHEILUS. 



Macronyona (Man. Conch. IX, pp. xxxii, 148). These Bulhni 

 are, therefore, just as genuine Helices as the genera Polygyra, 

 Acavus or Panda. The tendency to separate "Bulimoid" from 

 " Helicoid " genera seems in the light of present knowledge a wrong 

 one ; and it is daily becoming clearer that the character of shell- 

 contour is of quite secondary value. 



From the above definition and synonymy, the critical student of 

 malacology and its literature will at once and rightly conclude that 

 the present group is not only different in name from the genus 

 " Bulimus" as defined in Die Heliceen, Die Binnenmollusken Ven- 

 ezuelas, etc., but that it differs widely in limits also. Plekoeheilus, 

 Eurytus and Pachyotus formerly classed here, have been removed. 

 The former two have small eggs and consequently far smaller 

 nepionic shells, flagellum-bearing penis, finely plaited jaw, etc., all 

 features which effectually sunder them from the Strophocheilus and 

 Borus group. The distinction is not only visible to the anatomist, 

 but the comparative size of the embryo at time of extrusion from 

 the egg offers a good conchological feature observable in any spec- 

 imen having the spire perfect and unworn. Pachyotus is a group 

 reproducing by minute eggs and having various differential char- 

 acters to be more fully discussed later. 



History of the names Bulinus, Bulimus and Strophocheilus. 



1757. ADANSON, in his Histoire Naturelle du Senegal, Coquil- 

 lages, p. 5, pi. 1, Genus II, describes and figures under the name 

 " Le Bulin. Bulinns " a small fresh-water snail like a Physa but with 

 even-edged mantle, and belonging to the genus of Planorbince now 

 known under the names Bulinus, Ameria, Physopsis, etc. The ety- 

 mology of Bulinus is unknown, for most of Adansou's names are 

 new arbitrary combinations ; but it is likely that the French word 

 Bulle was its basis. As Adanson's names are not Linnrean in form, 

 and were published before the period universally adopted as the 

 starting-point of binomial zoological nomenclature, it is obvious that 

 they can properly have no bearing, whatever, upon modern nomen- 

 clature. When revived by post-Linnsean authors, they must date 

 from the time of such revival, without reference to Adanson's prior 

 use. Any other course would admit Adausonian names for a large 

 proportion of the Linnrean and Lamarckian genera. 



