66 



ARTIFICIAL TABLE 



OF THE GENERA OF BRITISH LAND AND FRESH-WATER 

 SHELLS. 



THIS table is merely intended to assist the student in 

 the discovery of the genera, without any reference to 

 their natural relations. The numbers refer to their 

 situation in the body of the work. 



I. UNIVALVES. Shells consisting of a more or less 



conical valve. 



A. Shell fiat, solid. 



7. LIMAX. Shell oval or oblong, without any visible spire. 



B. Shell conical. 



26. ANCYLUS. Shell conical, apex recurved rather to the right. 



27. VELLETIA. Shell conical, compressed ; apex subcentral, bent 



to the left. 



C. Shell ear-shaped, solid. 

 9. TESTACELLUS. 



D. Shell conical spiral. 



a. Shell thin, edge of lips not thickened or rejlexed, peristome not 

 continued. 



* Mouth transverse, lunate ; shell depressed, 



8. VITRINA. Shell imperforated ; mouth large. 



II. ZONITES. Shell perforated, or umbilicated ; mouth mo- 



derate. 



(Helices, Pupa, Clausilia, c., when young.} 



