94 MALACOZOA. GASTEROPODA. PULMOBRANCHIATA. 



in the district has the umbilicus so narrow, it being in fact 

 obliterated so as to present only a slight pit, or the aperture 

 so wide. It is certainly therefore a perfectly distinct species, 

 forming in some respects, especially in the mouth and umbili- 

 cus, a transition to the Genus Vitrina. 



First found by me, on the 27th June, 1841, on a bank 

 near Old Machar Cathedral, where it occurred along with mul- 

 titudes of Vitrina pellucida, and Pupa umbilicata ; in Sep- 

 tember, by Miss Macgillivray, in the Den of Auchmedden, 

 where it is not uncommon. 



It appears to be the species figured by Captain Brown, un- 

 der the name of Vitrina membranacea, and which he states 

 to have been found by him on the Lomond Hills, in Fife- 

 shire. In the young state, and when as yet only two or three 

 whorls have been formed, it presents a different aspect, the 

 mouth not having received its ultimate form. I have ob- 

 tained it in this state also, in which it appears to be repre- 

 sented by Capt. Brown's Vitrina margaritacea (Illust. PI. 40. 

 f. 54, 55, 56), from specimens found by Mr. Gerard amongst 

 moss on an old wall at Corstorphine Hill, near Edinburgh. 

 Specimens of Helix fusca, from Ireland, sent to me by Mr. 

 Thompson, agree entirely with my Aberdeenshire shells, un- 

 less in being a little less wrinkled and more glossy. 



Helix fusca. Mont. Test. Brit. 424. PI. 13. f. 1. Helix fusca. 

 Alder. Mag. Zool. and Bot. ii. 107. Helix fusca. Gray's Turton, 

 147. PI. 4. f. 36. Helix fusca. Flem. Brit. Anim. 264. Vitrina 

 membranacea. Brown, Illustr. PI. 40. f. 3, 4, 5. 



GENUS 4. VITRINA. GLASSY-SNAIL. 



Animal moderately elongated, spiral ; with the foot 

 large and depressed; four tentacula, the upper rather 

 long, all clavate ; the mantle protruding anteriorly so 

 as to cover part of the shell, and having a linguiform 

 process extending backwards externally on the right 

 side. 



Shell spiral, of few turns, semiorbicular, moderately 

 convex above, imperforate, extremely delicate, trans- 

 parent, glossy ; the last whorl disproportionately large ; 

 the aperture roundish, with a very thin margin. 



1. Vitrina pellucida. Green Glassy-Snail. 

 Shell ovate-orbicular, considerably depressed ; with tht 



