132 G. LINDSTRÖM, ON THE SILURIAN GASTROPODA AND PTKKOPODA OF GOTLAND. 



bilicus is visible and the aperture is ovate. lieight 21 uiillim., breadth 12 iiiillim. 

 Apical augle 38 °. 



It has been found in the coralliferous limestone of Lindeklint and Sandarfve 

 kulle, one specimeu from each locality. 



10. Murcliisonia munda n. 



Pl. XIII fig. 6. 



Shell turriculate, terete, with eight short, ventricose whorls, twice as broad as 

 high. The narrow, ropelike slit band forms a prominent angle a liltle below the 

 median line of the body whorl and a little above the same line iu the other whorls. 

 It is hemmed in by two distinct lines and its surface is prominent and convex, the 

 ereseents are distantiated, smooth, lameliar and imbricated, quite as in that group of 

 the Pleurotomarias, which has been called Crispa3. In this feature the four first species 

 of the Murchisonia3 ornata3 are similar. Above the band, and parallel with it, a small 

 ridge runs on the body whorl. The surface is transversally striated by gently undula- 

 ting, lameilar, densely placed lines, imbricated as it were. For the rest the shell is 

 quite smooth wilhout any longitudinal or transverse striee. The aperture is nearly 

 obliquely elliptic and the columellar lip thin and reflexed, hiding the umbilicus. 



Height nearly 6 millim., breadth 3 millira. 



A few specimens found in the marly strata of the upper limestone of Slite. 



It comes near to the preceding species as to the ornamentation, though this is 

 much liner in M. munda. 



11. Murchisonia tortuosa n. 



Pl. XIII fig. 4, 5, 13, 14. 



Shell turriculate, of nine ventricose whorls, nearly twice as broad as high, an- 

 gulated a little below the raiddle of the whorls, where the chordlike slit band is 

 placed. This band is narrow, convex and outstanding, composed of nearly tubular and 

 lameilar ereseents, which cover each other successively, in an imbricating way. The 

 lowest part of the whorls is abruptly bent in towards the suture in a face, whereby 

 the suture is uncommonly deep. There is a low ridge between the slit band and 

 the umbilicus parallel with the former. In one specimen, fig. 13 there are also two 

 or three low ridges on both sides of the slit band. The ornamentation consists for the 

 rest in transverse, sinuous, lamcllar striaj. On the umbilical part there is also much 

 variation, in some a succession of concentric ridges, cut by stria3, which are sinuous, 

 as in fig. 14, or in others, as in fig. 5, onl}' transverse striaä and concentric ones near 

 the edges. H. 11 mm., br- 6 mill. 



The aperture is ovate, the inner lip reflexed and hiding the umbilicus. 



