22 



For this interesting species, we are indebted to Capt. Le- 

 Conte, of tho Topographical Engineers, who informed me that 

 he found it in St. John's River, in Florida. 



It is most closely allied to the A. globosa, Swainson, a native 

 of the rivers of India. But that shell is rather less globose 

 and does not appear to have the almost regular, but slightly 

 elevated and very numerous undulations so perceptible towards 

 the aperture on the body whirl of this species; which has also 

 a few hardly perceptible, distant, brownish bands, particularly 

 towards the base. It may, however, be only a variety of that 

 species. 



As the name d^pressa, of the Appendix to Long's Expd. p. 

 "2Qi, is preoccupied by Lamarck for a fossil species; it may be 

 changed to paludosa. 



A.ftngrflata. Shall subglobose, olivaceous brown, with 15 or 

 16 revolving, dull reddish brown, slender bands: spire conic, 

 moderately elevated, acute: boiy whirl regularly rounded, more 

 obviously undulated or obtusely wrinkled near the aperture: 

 umbilicus free, obvious: labrum a little dilated: within reddish 

 brown: labium, columella, and margin of the labrum white: 

 operculum horny. 



Length, over one inch and a half; greatest width, one inch 

 and two-fifths. Inhabits Mexico. 



Occurs in plenty a short distance below Vera Cruz. We 

 found them immediately behind the sand-hillocks of the coast, 

 in situations which, in rainy seasons are covered with fresh 

 water. We did not see a living specimen; they were mostly 

 decorticated and bleached. Than A. depressa, Nob., (changed 

 to paludosa, Nob., as the name is preoccupied,) it has a more 

 elevated and acute spire, larger umbilicus and more regularly 

 rounded body whirl. I am unacquainted with the A. linearis, 

 Perry, which he supposes to be a native of the coast of North 

 America. 



VALVATA, Mull. 



V. humeralis. Shell subglobose, depressed: spire convex, not 

 prominent: whirls three and a half, with the shoulder depress- 

 ed, plane; wrinkled across, or rather with slightly raised lines: 

 aperture appressed to the penultimate whirl, but not interrupt- 

 ed by it: umbilicus rather large. 



Greatest breadth, less than one-fifth of an inch. Inhabits 

 Mexico. 



