1822.] occurring in the E7ivirons of Btistvl. 377 



Observation, — 1 perfectly agree with Dr. Maton in considering 

 M. avanensis only a variety of M. anatina. Miss Bennett, of 

 Nortonhouse, favoured me lately v^^ith specimens from Tisbury, 

 Wiltshire. They are old shells, and from the animal having 

 lived, in water, highly impregnated with chalk and calcareous 

 matter, its epidermis has secreted so rapidly, and increased the 

 shell so much in thickness, that the Linnean character " testa 

 fragilissima " is entirely lost. 



7. Bulla hypnorum. In ditches. 

 Physahypnorum. Drapernaud. 



8. Bulla fontinalis. In ditches. 

 Physa fontmalis. Drapernaud. 



9. Voluta denticulata. In the Avon below the Hotwells. 



Observation. — Its columella does not continue to the com- 

 mencement of the spire, which is empty, and shows no spiral 

 »epta. 



iO. Buccinum terrestre. On Leigh and Clifton Down. 

 Bulimus acicula. Drapernaud. 



11. Turbo elegans. In Leigh wood, 8cc. ' 

 Cyclostoma elegans. Drapernaud. 



12. Turbo fontinalis. In ditches. 

 Cyclostoma obtusum. Drapernaud. 



13. Turbo nautileus. In ditches. 

 Planorbis cristatus. Drapernaud. 



14. Planorbis imbricatus- Drapernaud. In ditches and 

 pools. 



15. Turbo cristatus. In ditches. 

 Valvata sperorbis. Drapernaud. 



16. Valvata minuta. Drapernaud. 



Observation. — Of this, I have only found two dead shells in 

 the drifted sand, &c. on the Banks of the Avon. 



17. Turbo laminatus. Leighwood. 



18. Turbo nigricans. Leighwood. 



19. Turbo Everetti Qiobis)^ on willow trees, near river banks. 

 Spec. Char. A turretted, fusiform, ventricose striated, 



brown, opaque shell, with nine reversed volutions. Aperture 

 with two teeth. 



Observation. — I consider this a distinct species, it having only 

 nine volutions, whereas T. nigricans has always twelve. I have 

 named it after W. Everett, Esq. of London, a gentleman zealous 

 in the study of British conchology. 



Obser. a. — Montagu states the frequent occnrXence of turbo 

 laminatus and nigricans deprived of their brown epidermis. But 

 I have suites of specimens of all the three species in various 

 stages of growth, which have a white epidermis, show no mark 

 of being worn, and are evidently interesting, though rare 

 tvarieties. 



Obser. b. — As I frequently make sections of shells by grinding 

 them down to come at the details of their internal formation, I 



