APPENDIX. 317 



greatly perplexed the conchologist, and the condition of my fossils presents greater difficulties in their 

 determination. 



In the 'Memoirs of the Geological Survey,' vol. i, p. 423, Lacuna Montacuti is quoted as having been 

 found in the Drift Beds of Ireland. 



Littorina ? suboperta, 'Crag Moll.,' vol. i, p. 118, t. 10, fig. 13. Since the figure here referred to 

 was made, I have obtained a rather better specimen, which shows a flattened or slightly concave columella, 

 the characteristic distinction of the genus Lacuna. It may, perhaps, with more propriety be called Lacuna 



suboperta. 



Littorina neritoides, rudis, and palliata, are enumerated in the ' List of Clyde Fossils.' 



FOSSARUS SULCATUS, S. Wood. 



PHASIANEMA SULCATA. 8. Wood. Catalogue, 1840. loc. cit. 

 FOSSARUS CLATHRATUS. Id. Crag Moll., vol. i, p. 121. 



The Crag shell was considered by myself as an id entity with the Mediterranean species, which subse- 

 quent examination gives reason to believe is not correct ; I have, therefore, ventured to restore to it the 

 provisional name given in my 'Catalogue.' It resembles a recent British shell which I believe belongs to 

 this genus, Odostomia dolioliformis, 'Hist. Brit. Moll.,' vol. ii, p. 301, pi. 97, fig. 5. Our fossil is, however, 

 specifically distinct, and seems to preserve an intermediate character between dolioliformis and clathratus, 

 being larger than the one, and smaller than the other, and more elongated than either. The ridge upon 

 the columella is at times invisible, and is a character not to be depended upon. 



ODOSTOMIA UNIDENTATA, Montague. Tab. XXXI, fig. 11. 



TURBO UNIDENTATUS. Mont. Test. Brit., p. 324, 1803. 



VOLUTA UNIDENTATA. Mat. and Rack. Trans. Lin. Soc., vol. viii, p. 121. 



JAMINIA UNIDENTATA. Brown. Illust. Brit. Conch., pi. 50, figs. 34, 35, 1827. 



ODOSTOMIA UNIDENTATA. Forb. and Hani. Hist. Brit. Moll., vol. iii, p. 264, pi. 95, 



figs. 7, 8. 

 PLICATA. Flem. Brit. An., p. 310, 1828. 



Spec. Char. Testd minutd, ovato-conoided, Icevigatd, anfractibus 5 6 convexiusculis , spird paulo 

 longiore, aperture ovatd, labro simplici, columelld unidentatd. 



Shell small, ovately conical, smooth, with about five or six volutions, slightly convex ; spire a little 

 longer than the aperture, which is ovate, with a simple lip ; columella toothed. 



Length, T ' ff inch. 



Locality. Red Crag, Walton Naze. Recent, Britain. 



A solitary specimen of a shell of this perplexing genus has been recently obtained by myself from 

 the Red Crag, and it appears to accord best with the shorter variety of the above-named recent British 

 species, although it differs slightly in having the volutions at the base rather more rounded. 



In the former part of my Monograph, Od. plicata and Od. conoidea are united as one and the same 

 species, which I now believe to be distinct, as pointed out by the authors of the ' Hist, of Brit. Mollusca.' 

 Both these species were in existence during the Crag Periods, the latter in the Coralline, and the former 

 in the Red Crag. 



A shell in my cabinet, from the Coralline Crag, strongly resembles Od. eulimoides ; but the specimen 

 is not in sufficiently good preservation for figure or description. 



