166 



come the Valvata, few in species and minute, with shells of elegantly 

 spiral or discoid growth. 



Ampullaria. Paludina. Valvata. 



Genus 1. AMPULLARIA, Lamarck. 



Animal ; globular or subdiscoid, with the dish mostly large and 

 thin, oblong-square or triangular, broadly truncated in front. 

 Head flattened, terminating with a pair of tentacles, below 

 which is another pair longer and more slender, and below these 

 a pair of eyes sometimes sessile, sometimes mounted on pedicles. 

 On the left side of the body is a conspicuous respiratory canal, 

 formed by a fold of the mantle, leading to a pair of pectinate 

 gills ; in front is an open pulmonary cavity. 



Shell ; globose or ovate, more or less umbilicated, rarely imper- 

 forated, covered with a rather thick olive epidermis ; suture of 

 the spire sometimes simple, sometimes channelled ; whorls more 

 or less ventricose, smooth ; aperture rather large, lip simple. 

 Operculum sometimes horny, sometimes calcareous, closing the 

 aperture. 



The sombre hue and obvious similarity of form, destitute of any indi- 

 cation of sculpture, of the shells of Ampullaria, have led to this genus 

 being very much neglected by the collector ; and their unattractive range 

 of habitation, in swampy marshes, ponds, and rivers, has not been very 

 inviting to the traveller. A few ardent naturalists, including among the 

 foremost M. d'Orbigny and Mr. Bridges on the banks of the great rivers 

 of Bolivia, Dr. Spix . in Brazil, M. Caillaud in Africa, Mr. Yates and Mr. 

 Wallace at the rivers Marailon and Amazon, MM. Salle and Ghiesbrecht 

 in Mexico, Mr. Dyson in Honduras, Mr. Benson in India, and Mr. 

 Layard and Mr. Templeman in Ceylon, have directed their energies since 

 Lamarck's time to Ampullaria-hxmtmg ; and the result of their labours 

 enabled me to describe in the ' Conchologia Iconica' a hundred and thirty 

 species, of which scarcely a dozen were known to Lamarck. 



The species of Ampullaria are exceedingly well defined, though bearing 

 great general resemblance, and, what is not usual with mollusks affecting 

 such habitats, many of them are stained at the aperture with brilliant 

 colour. The animal is of an amphibious nature, possessing a double 

 system of respiration, which adapts it to breathe either air or water, ac- 

 cording to the requirements of the place of its habitation, which may be 



