160 G. LINDSTROM, ON THE SILURIAN GASTROPODA AND PTEROPODA OF GOTJLAND. 



transverse imbrication dense. The oldest form from the lowest beds of the marly 

 shale of Wisby (PI. XVII f. 5 — 7) is turbinate, with only three longitudinal keels and 

 a low one around the umbilicus. The ornamentation is for the rest the same. 



This Or. ruffosum differs from Or. discors in the more distantiated, transverse 

 laminae and in their folds being considerably reflexed backwards on the keels. Such 

 a variety of 0. discors as that figured pi. XVII f. 1 — 2, connects both. 



3. Oriostoma contrarium n. 



PI. XX fig. 8—15. 



Shell sinistral, turbinate, with six terete whorls. The apex is sunken and the ex- 

 treme tip is hidden beneath the next whorls, fig. 15. The surface is transversally and 

 obliquely striated by regularly distantiated lamellar ribs, often dividing in two and 

 again uniting, a little wavy in their edge, which is sharp and thin. They are curved 

 sigmoidally upwards towards the umbilicus. The aperture is obliquely ovate or even 

 circular with thin lips and continuous peristome. The inferior part of the exterior lip 

 is folded in and thus narrowing the aperture. The umbilicus is wide and large. It 

 is defined by a narrow ridge, which is most prominent in young or small specimens, 

 fig. 13, indistinct or only as a swelling in the older. The shell substance is thick, 

 especially in the body whorl. Owing to the different state of preservation the aspect 

 of the surface varies, being corroded in some and only the basal lines of the lamellae 

 left, fig. 14- H. 24 millim., br. 41 millim. Another specimen has in h. 24 mill., br. 

 23 mill. 



It has been obtained from the shale of Wisby, from the limestone beds of Lansa 

 and Lutterhorn in Faro, Wialmsudd, Samsugn in Othem, the canal of Westoos in Hall, 

 Kyrkberget in Wisbj' and Hoburg. 



4. Oriostoma globosum Schlotheim. 



PL XYII, fig. 24, 25, 29—31, pi. XVIII, fig. 24, pi. XX, fig. 16. 



y Valuata sulcata 1776. Walch, der Naturforscher, Neuntes Stiick, 278, tab. IV f. 5. 



DelpJmmla 1811. Parkinson Orgauic Kemains, 78, tab. Y. f. 18. 



Trochilites glohosus 1820. Schlotheim Petrefactenkuude, 162. 



Euomphalus funatus 1823. Sowkrby Miner. Conch, vol. V, 71, tab. 450 f. 1 4 2. 



1839. Id. Sil. Syst., 626 pi. 12 f. 20. 



1843. Morris Cat. Brit Foss., 144. 



1848. Bkonn Nomenclator, 479. 



1849. Brown Illustrations of the fossil Concholoev of Great Britain and Ireland, 81, pi. 



XLII figs. 24, 25. 



1854. Morris Catal. 2d Ed. 248. 



1855. Mac Coy Pal. Foss., 298. 

 1858. Fr. Schmiut Geol. Estl., 202. 

 1862. M'CoY Sil. Foss. of Ireland, 13. 

 1867. Salter Sil. ed. 4, 531, pi. 25 fig. 3. 



1871. Baily Charact. Brit. Fossils, pi. 21 f. 9a, 9b. 

 1873. Salter Catal. Cambr. Foss., 90, 157. 



