108 On the Land and Fresh Water Mollusca 



21. Alliaria, Miller. 



var. H. glabra, Studer ? 

 Mr Gilbertson finds what he considers to be a variety of this 

 species, much larger than the usual size. This variety appears to 

 be the H. glabra of Studer (Ferussac, Tab. des Moll. No. 215,) 

 judging from specimens in M. de Ferussac's cabinet. 



22. Cellaria, Mull. 



Continental specimens of this shell are larger and rather more 

 open in the umbilicus than British ones, which induced M. de Fe- 

 russac to think that they might be distinct. The same remark is ap- 

 plicable to H. nitidula, but in both cases, I think, amounting to no- 

 thing more than a variety. H. nitens, Fer. Tab. des Moll, is only 

 the English variety of this species in a small state. H. nitens of 

 Michaud, if we may judge from the figures, is H. nitidula, Drap. 

 I suspect his H. nitidula is, like that of Pfeiffer, the var 0. of Drap., 

 and H. radiatula of this catalogue. 

 23. Pura, Aid. 



var. H. nitidosa, Fer. 

 Much confusion has arisen in the attempt to ascertain the H. ni- 

 tidosa of Ferussac, Tab. des Moll, of which neither figure nor de- 

 scription has been published. This arises from his quoting H. niti- 

 dula, var a. Drap. as a synonym. There happens to be no var. a ; 

 but the var. /3, which, from his reference to the figures, Ferussac 

 must have meant, is our H. radiatula. His specimens are undoubt- 

 edly the horn-coloured variety of our H. pura. 



24. Crysiallina, Mull. 



H. hyalina ? Fer. Tab. des Moll. No. 224, appears to be a 

 variety of this. 



25. Fidva, Drap. 



var. H. Mortoni, Jeff. 

 A difference of opinion exists between English and continental 

 naturalists, as to whether this species is the H. Trochulus or H. 

 fulva of Muller. This it is impossible now to decide. It is certain, 

 however, that the species now under consideration is the H. trochi- 

 formis of Montagu, and H. fulva of Draparnaud. Ferussac has cal- 

 led another shell H. trochiformis, and as Draparnaud's name is more 

 generally adopted, it is better to acquiesce in it. H. Mortoni, Jeff, 

 is, I think, only a depressed variety of this. There is a small varie- 

 ty, not uncommon, darker coloured, and with very delicate and beau- 

 tiful concentric striae on the base, only visible with a high magnifier, 

 which I at first considered distinct, but on closer examination, slight 

 traces of these striae are also visible on full-grown and decided speci- 

 mens of H. fulva. I have therefore not ventured to separate them. 



