116 G. LINDSTKOM, ON THE SILURIAN GASTROPODA AND PTEKOPODA OF GOTLAND. 



which is tlie slopiiitf, interior uiiibilicul side iuid the both i'(|ual sides lire the exterior 

 and the apieal sides. There is thus a narrow ridge runnini,^ along the middle of the 

 umbilieal side, being in older whorls as thin as a knife edge. The ornaiuentatioTi con- 

 sists of transversal, regularly distantiated, narrow lines, somewhat wavy and enclosing 

 between them numerous, minute lines, parallel with them. When reaching the wing 

 of the slit band tiiey are bent in a gentle curve backwards. On the umbilieal side 

 the sculpture is uiore coarse and consists of imbricated lamellaj. 



Length of whorl and slit band near the aperture 21 millim. Length of slit band 

 alone 10 millim. Breadth of whorl near the aperture 10 millim. 



Only one specimen has liitherto been found in a detached stone on the shale 

 beds near VVisby, which probably, as far as can be judged by the rock, belongs to the 

 Upper Silurian of Gotland and the oldest shale. 



This species is related to Eccyliomphalus alatus 1'erd. Koemek Leth. Geogn. 187(), 

 tab. 5 fig. 5, in wliich, however, the apieal spire is elevated into an apex on the um- 

 bilical side, the slit band is shorter and the section of the whorls is rather more oval 

 than triangular. E. alatus or a nearly related species also occurs in the Upper Red Or- 

 thoceratite limestone of Gland, while another, which comes near to Pleurotomaria repli- 

 cata, has been found in the Upper Gray limestone of Dalecarlia. These fossils have 

 been numbered with Eccyliomphalus, but I shall further down attempt to show that 

 this genus cannot be retained, as it contains either evolute Pleurotomariii? as this 

 species and kindred, or evolute Euom|)hali, the peculiarity of the uncoiled whorls being 

 in no way any characteristic sufficient enough for generic distinction, when taken alone. 

 This PI. replicata is a direct development from such forms as those described with 

 PI. qualteriata and connects them with tlie group Alatie, being probably in genetic 

 connection with the fourth of these Qualteriataj. 



28. Pleurotomaria alata Waulenberg. 



PI. X, tig. la— 32. 

 Cornii Ammonis lajvis vestigium. 173U Bromell, Lithogr. Svec. iii Act. liter. Scieut. Svec. p. 31. 



Turitiales alatus 1818. Waulenbekg Petief. Svec, 69. tab. Ill I'. Ij — 8. 



1828. llisiNGEK Aiiteckii. IV, 221, 237. 



Turbo alatus 1824. KoNlG Icoiies fossilium sectiles, pi. IX tig. 107. 



Delpliinula alata 1829. Uisingeii Tableau ed. 1, 10. 



1831. Id. Aiitecku. V, 113. 



1831. Id. Tabl. ed. 2, 8. 



Kuunijihalus alatus 1829. Brongniaiit Tableau des teiiains, 428. 



1837. HisiNGKii Lethiiea, 36, tab. XI f. 7 a— b. 



1839. Angelin Museum PaUeontologicum Scaiidiuav. N;o 31). 



1839. SowERBY Sil. Syst., 631, pi. 13 I'. 28. 



1841. HisixGER Forteckii., .55. 



1843. MoRUis Brit. Fossils, Ed. 1, 144. 



1847. MURCHISON Quart. Jouru. Geol. Soc, 29. 



1848. Bronn Nomenclator, 478. 



1848. Phillips Mem. Geol. Survey II, i, 356. 



