84 G. a.INDSTKÖM, ON TlIE SILUUIAN GASTKOPODA AND l'TEROPO])A OF GOTLAND. 



and the saddle of tlie interiör lip is hirge,. The keel is blunt to jndge by tlic cast 

 of it. Heiglit of the shell 33 niillini., breadth 23 luillim. lleight of aperture 20 mil- 

 lim., breadth of same 15 millim. 



Only one specimen has hitherto beeu found in the limestone of Martebo. 



4. Cyrtolites obliquus n. 



Pl. VI ligs. 54—55. 



Shell discoid, a little obliqiiely involute, terete; ornamental striaj riaost ininute, 

 closely set, with denticulated edges, dorsal carina blunt and narrow. Whorls three and 

 a half. Diameter of the fragmentary shell 3 millims. From the sandstone of Bursvik. 



5. Cyrtolites euryomphalus n. 



Pl. VII ligs. 10—15. 



Shell diseoid, involute, surface smooth, rather glossy, ornamented with regularly 

 distantiated Ijnes, elevated, giving the surface an imbricated appearance. Along the 

 interiör edge of the whorls there runs a narrow ridge, on which the transverse lines 

 swell in a minute nodule. From this ridge the surface falls off abruptedly towards 

 the centre of the shell. The whorls are four and a half, gradually increasing in width, 

 contiguous. The aperture is broader than long, nearly pentagonal, with the dorsal ca- 

 rina forming a tonguelike processus from the superior edge. The slit band is inuch 

 prominent, flat on its outer edge and covered with distantiated, crescent shaped lines 

 of gi'owth. Diameter 5 millim., breadth of aperture 3 millim.; height 2 millim.; dia- 

 meter of space enclosed within the interiör ridge 2 millim. From the shale at Djup- 

 vik in Eksta. Souie twenty specimens known. A corroded specimen has also been obtained 

 from the sandstone of Bursvik. 



6. Cyrtolites discus n. 



Pl. VII figs. 18—21. 



Shell discoid or lenticular, slightly tumid, surface with liuear, elevated, trans- 

 verse striie, cnrved gently backwards on the dorsal side, regidarly distantiated and hav- 

 ing between them much finer, minute lines. Whorls four, gradually increasing, the 

 last one partially free. Aperture triangulär, lower lip nearly straight, horizontal, lateral 

 margins faintly curved, converging at the narrow dorsal slit. Slit band narrow, eleva- 

 ted, blunt, not much prominent, covered with small crescent shaped lines of growth. 



Largest diameter 7 millim., breadth 3 millini. 



The original specimen, which belongs to the Museum of the Geological Survey 

 of Sweden, has been found in the sandstone of Bursvik. Låter, another specimen has 

 been found in the middle limestone beds near Wisby. This is more smooth without 

 any smaller lines between the large transverse strias. 



