486 New Genus of Land Shells. • 



The animals of these shells,'like the Andstoma, &c, must remain satisfied 

 with its size, after they have once formed its mouth, as they cannot 

 alter it by reabsorption, as many of the Helices do, without removing the 

 whole of the last whorl ; for, if a new whorl were added to it, it would en- 

 tirely alter the form of the shell. 



A. Shell depressed, oblong, very oblique. Mouth with a Tooth on the inner Lip . 



Periostraca thin, polished. Umbilicus linear, closed. 



1. Streptdxis comboldes ; Helix comboides IfOrbigny Voy. 

 Inhabits South America. 



M. Moricand {Trans. Acad. Geneva) describes two varieties; one from 

 Brazils, and the other from Bolivia. 



2. Streptaxis Maugerce {fig. 60. c, d.") Shell oblong, white, thin, trans- 

 parent polished ; the three upper whorls regular, the last and last but one 

 very much distorted. 



The young shell (d) is depressed, polished (sometimes with a few 

 small crenulations near the suture). The umbilicus is very large and 

 deep, showing the volutions. 



Inhabits Sierra Leone. Mr. Speck, Mrs. Mauger's, and my cabinet. 



B. Shell rather depressed. Subhemispheric, thin, rather oblique. Inner Lip 



toothless. Periostraca thin. Umbilicus deep. 



3. Streptdxis contiisa ; Helix contiisa Ferussac, t. 31. f. 1. ; Copied Wood 

 Supp., t. 7. f. 29. 



Inhabits Brazils. My cabinet. 



The front of the last whorl smooth, rest of the shell closely concentri- 

 cally striated. 



C. Shell convex, rather top-shaped. Whorls many, rather oblique. Um- 



bilicus small, deep. Inner Lip toothless. 



4. Streptdxis deformis ; Helix deformis Ferussac, t. 32. f. 1.; Cop. Wood 

 Cat. Supp., t. 7. f. 40. 



Inhabits Brazils. My collection. 



D. Shell ovate, thin. Whorls many, oblique. Umbilicus linear, closed. 



Inner Lip toothless, very thin. 



5. Streptdxis nobilis. (a, b.) Shell thin, whitish, pellucid. Whorls 6, regu- 

 larly transversely grooved j the front of the hinder part of the last whorl 

 learly smooth. 



Inhabits Sierra Leone. Mr. Speck, collection of the British Museum, 

 Mrs. Mauger's, and my own. 



The epiphragma, which exactly closes the mouth, is nearly flat, rather 

 convex in front, with minute curved cross lines, forming, two series, curving 

 round a subcentral cross groove, and all arising from the hinder angle of 

 the mouth ; where it is inflexed, and where there is left a small slit, through 

 which the animal doubtless respires. The epiphragma is evidently first 

 deposited as a thin convex membrane, as is shown by the lines on the 

 surface, which are afterwards thickened by an internal shelly coat. 



E. SheU ovate, solid. Last Whorls slight, oblique. Umbilicus closed, linear 



Inner Lip thickened, with a Tooth on the outer Side. 



6. Streptdxis ? Pagoda ; Helix Pagoda Ferussac ; Helix concamerata 

 Wood Cat. Supp., f. 21. 



Inhabits Magadascar. My collection. 



This last species appears to be intermediate between this genus and the 

 genus Gibbus of De Montfort, of which Brilemus Lionetteiinus is the 



