184 G. LINDSTROM, UN THE SILURIAN GASTROPODA AND PTEROPODA OF GOTLAND. 



sists of minute and closely set transverse, nearly straight stria?, crossed by more ir- 

 regular, wavy, impressed, longitudinal lines. The aperture is obovate, almost as in Cr. 

 elegantulum, but situated deep beneath the outgoing frame, which above is prolonged 

 in the characteristic spurlike process and below in an obtuse lappet. The interior 

 lip is bifid in the same manner as the others. On the outside of the body whorl near 

 the aperture there is a transverse, shallow groove dividing the enlarged apertural frame 

 from the deeply hidden aperture proper. This frame is here as in Craspedostoma ele- 

 gantulum very thin and sharp edged. H. 10 mill., br. 13 mill. 



Two specimens have been obtained from Klinteberg and one from Samsugn. 



.5. Craspedostoma involutum n. 



PI. XXI fig. 39—42. 



Shell small, globose, helicoid, whorls five, spire short but prominent, the trans- 

 verse ribs numerous, close, with frilled edges where they meet the longitudinal stv'ise, 

 which resemble those of the other species. The aperture is obovate, acuminate below, 

 the broad frame is broken away. The inner lip is bifid as in the others, its outer 

 branch straight and somewhat thickened, but its inner branch does not continue straight 

 down as in the others, it is convoluted around the central axis of the conical hollow 

 which it forms and thus hiding the umbilicus: h. 9 millim., br. 11 millitri. 



Four specimens have been found in tlie highest limestone stratum of Wisby on 

 Kyrkberget. 



6. Craspedostoma glabrum n. 



PI. XXi fig. 43—54. 



Shell globular, small, naticoid, thin, whorls five, with short, though prominent 

 spire and the body whorl many times surpassing the others in size. Surface apparently 

 smooth with only a few, much distantiated, transverse sigmoid ribs, which are faintly 

 prominent with an obtuse edge. Between them the surface is most distinctly longitu- 

 dinally striated by somewhat wavy and graduated lines and transversally to them and 

 parallel with the ribs there are microscopically minute lines. The aperture is circular 

 or obovate, environed by exceedingly broad, refiexed lips, forming a large frame around 

 it, of such enormous size that in relation to it the shell looks as an appendix. This 

 frame is prolonged in a large, acuminated spur near the umbilicus, which it nearly 

 completely covers and its lowest corner near the spire is also elongated in a triangu- 

 lar spur. The surface of the frame is finely lineated by the parallel, superimposed strata 

 of growth of successive lips, giving it an imbricated appearance. The umbilicus is 

 narrow. Only the largest specimens are provided with an inner branch of the inner 

 lip. H. 18 mill., br. 13 mill., breadth of aperture 11 mill. 



Most abundant in the red and gray limestone of the hill of Sandarfve. 



