134 G. LINDSTROM, ON THE SILURIAN GASTROPODA AND I'TEROl'ODA OF GOTLAND. 



14. MurcMsonia cocMeata n. 



PI. XIII fig. 2—3. 



Shell turriculate, slender and tapering with twelve or thirteen whorls, much an- 

 gulated and prominent along the median line. The sides of the whoi'ls on both sides 

 of the slit band are rather much more concave than in any of the preceding species, 

 and constricted into a vertical ring near the lower suture. The slit band is promi- 

 nently convex, hemmed in only by the uneven edges of the surface, and covered by 

 very unequal, regularly curved crescents of which some prominent are mingled with 

 fainter. The ornamentation on both sides consists of transverse, much curved, ele- 

 vated sulci, remote, the interstices striped with minute striaj. On some distance from 

 the slit band tliree or four elevated ridges are crossing them; the largest is placed at 

 highest above the band, encircling the umbilical surface. On this same surface tliere 

 are several others, low, concentric ridges, which are crossed by finer and more closer 

 striae. The aperture is nearly circular and the columellar lip largely reflexed, widened 

 in a broad lamina near its superior corner and hiding the opening of the umbilicus. 

 The suture is distinct and slightly impressed. H. 18 inilliin. br. 8 millim. 



This s|)ecies has been found in some 30 specimens in the red limestone of Sand- 

 arfve kulle and also a few from the limestone of Katthammarsvik in Ostergarn. 



15. Murchisonia deflexa n. 



PL XX lig. 1—6. 



Shell turriculate, with nine transverse, tumid whorls, carinated through many sharp, 

 longitudinal keels. The whorls rapidly increase in size in the following regular proportion : 



the breadth thus increasing exactly in the double ratio of the height. A longitudinal section 

 of the wliorls gives an oval, nearly pyrifoi'm outline, broadest above and narrow below. 

 The slit band, the greatest peculiarity of this species, is situated a little above the 

 median line of the whorls. It is a narrow and excavated gi'oove, covered with 

 oblique crescents. Its superior, bordering line has grown out in a vaulted lamella, which 

 is bent down over the band so much that it completely hides it and its surface only 

 can be seen where this lamella is broken. This superior lamella is thin and sharp 

 edged, like a claw in the section, the inferior bordering line again is short, blunt and 

 horizontal. As seen in the section, tig. 6, the slit continues open along half the 

 body whorl. The surface on both sides of the slit band is delicately and finely cancel- 

 lated by lines of Avhicli the transversal ones above the slit band curve backwards only 



