AMPULLARIA. 



and meeting on their straight edges:"* two 

 very long and slender tentacles arise from the 

 base of the head, and are provided with ocu- 

 liferous peduncles at their external base: "ovi- 

 parous, sexes distinct, the female being much 

 larger than the male: mantle simple, except that 

 the upper left wing is extended so as to admit 

 of being rolled up into a tube occasionally:")"" 

 foot large, thin, truncated in front, with the 

 sides parallel, or converging towards the pos- 

 terior extremity, which is rounded, and bears 

 the opercle. 



SHELL globular, ventricose, generally umbili- 

 cated, and covered with a periostraca; aperture 

 oval, spire short, body whirl much the largest. 



HABITS. A. depressa is found at Hopeton, 

 a swamp plantation on the banks of the Alata- 

 maha river in Georgia, U. S., about fifteen 

 miles from the sea; moving along the bottom 

 and sides of muddy ditches, in stagnant water, 

 and sinks by expelling the air which has been 



* J. H. Couper, in letters. 



f Ib. Guilding describes another and shorter siphon 

 upon the right side. 



