170 MANUAL OF THE MOLLUSCA. 



on the coast of Cornwall, congregated in little groups, about a foot or two 

 from the surface of the sea, where the waves break over them. They ascend 

 and descend, so as to maintain their distance as the tides rise and fall ; but 

 will not bear long immersion in sea-water. (Couch.) 



? Buchanania (oncidioides) Lesson. Named after Dr. F. Hamilton 

 (Buchanan), the Zoologist of India. Animal oval, entirely covered by a 

 simple mantle ; respiratory orifice in the centre of the back ; head with 4 ten- 

 tacles, retractile beneath the mantle; foot oval, much smaller than the 

 mantle; length 3^ inches. Coast of Chile. (Requires confirmation.) 



VAGINULUS, Ferussac. 



Type, V. Taunaisii, Fer. Syn. Veronicella, Bl. 



Animal elongated, slug-like, entirely covered by thick coriaceous mantle, 

 smooth or granulated; head retractile under mantle; tentacles 4, upper 

 pair slender, cylindrical, inflated at the tips and bearing eyes, lower pair 

 short, bifid ; foot linear, pointed behind ; sexes united ; $ orifice behind the 

 right tentacle, ? midway on the right side, beneath the mantle : respiratory 

 and excretory orifices at posterior extremity, between mantle and foot. In- 

 habits forests, in decayed wood and under leaves. 



Distr. 6 sp. W. Indies, S. America, India, Philippines. 



FAMILY IV. LIMN^ID^:. 



Shell thin, horn-coloured ; capable of containing the whole animal when 

 retracted ; aperture simple, lip sharp ; apex sometimes eroded. 



Animal with a short dilated muzzle ; tentacles 2, eyes sessile at their 

 inner bases; mouth armed with an upper mandible, tongue with teeth similar 

 to Helix. The Limnseids inhabit fresh-waters, in all parts of the world ; they 

 feed chiefly on decaying leaves, and deposit their spawn in the form of oblong 

 transparent masses, on aquatic plants and stones. They frequently glide be- 

 neath the surface of the water, shell downwards, and hybernate or restivate 

 in the mud. 



Fig. 95. 



Lamarck. Pond-snail. 

 Etym. Limnaios, marshy. Type, L. stagnalis, fig. 95. PI. XII. fig. 30. 



* Adjectives employed as names for shells should have the feminine termination. 



