KONGL. SV. VKT. AKADiaHEN.S ITAN])L. BAND. 19. N:0 6. 119 



few speciraens ol" Pl. alata, lig. 28, which also show a very faint rib nearly on the sarne 

 place as in the variety. Height 8 millim.; breadth 16 rnill. 



From Djupvik in Eksta, Lingsarfve in Näs, Fårö, Westergarn and in the oolitic 

 limestone of Bursvik. 



30. Pleurotomaria alata var. opposita n. 



Pl. X. %. 38—40. 



Shell trochiform, broader than high, spire of five or six whorls, raore ventricose 

 than in the preceding varieties of the species. Slit band situated a little above the me- 

 dian line of the whorls. Beneath the band, near the suture, a narrow keel is seen and 

 there is none around the umbilicus. This variety is best distinguished by the direc- 

 tion of the transverse strias, which, as seen in fig. 39, are raore prominent and elevated 

 than in the others and are obliquely turned against the aperture, quite opposite to 

 what obtains in most of the other Pleurotoraariaä. The ends of the larger stria? radiate 

 in an expanded brush of minute striae, lig. 40. In the preceding forms the striaa meet 

 the slit band either rectangularly or directed backwards. Height 7 mill., breadth 13 mill. 



From the shale at Petesvik in Habblingbo. 



31. Pleurotomaria prsetexta n. 



Pl. XI iig. 1—7. 



Shell trochiform, moderately elongated, with six whorls, which are convex and 

 evenly rounded below, the umbilical side almost flat. The keel formed by the slit 

 band is broad, near its junction with the whorls on both sides ornamented with a 

 strongl}' prominent, spiral ridge, on which the transverse strite form nodules. The band 

 is placed a little above the median line of the body whorl and on the other whorls 

 high up, close to the suture. As seen in fig. 5 its interiör crescentic lamellai are very 

 closely packed, elongated and reach obliquely forwards to the margin of the keel. This 

 margin, fig. 6, is sometimes folded in a number of small wavelets, nearly as in 

 Pl. undulans though more regularly. The transverse stria?. of the surface are ap- 

 proached, although at regular distances, and have some smaller, parallel ones in the 

 interstices. The aperture is circular and a little angular in its interiör corner and the 

 umbilicus open and narrow. Height 13 mill., breadth 16 mill, aperture 6 millim., um- 

 bilicus 3 millim. 



Occurs in the lowest shale beds near Wisby. 



This species is nearly related to Pl. alata, from which it is readily distinguished 

 by the elevated ridges near the edge of the slit band. 



32. Pleurotomaria togata n. 



Pl. XI fig. 8—1.3. 



Shell trochiform of seven angular whorls, slit band thick and short, fig. 13, 

 placed above the median line of the body whorl and close below the suture in the 



