68 G. LINDSTRÖM, UN TllE SILUKIAN GASTKOPOUA AND PTEKOPODA OF GOTLAN]). 



verse lines. The grooves formed by these are deeper in the specimens from Sandarfve, 

 tliaii from VVisby. In the speeimens from Klinteberg, ligs. 10, 10a, the sculpture is 

 only discernible on the apex. On the body whorl it is quite obliterated and covered 

 by coarse transverse lines of growth. The whorls are tive, tumid and globose, the 

 body whorl being many tinies larger than the preceding ones. The suture is decp 

 and narrow. The aperture is oval, longer than broad. The lips are continuous 

 all round the aperture in the adult, pl. III figs. 10, 13; fig. 11 probably still 

 young. The margins of the aperture are widely refiexed, so as to give it a trumpet- 

 shaped form. As seen in tigures 10a, 13 & 14, the aperture is thickened through the 

 accumulation of the lameilar lips. Especially this is evident in specimens from the 

 fine-grained limestone of Sandarfve kulle in which a great number of apertural laraellaj 

 are preserved. Pl. III fig. 17. There are in this instance no less than seventeen such 

 reflexed, apertural lamelk"e left behind in their old place during the progressive growth 

 of the shell. Seen through a microscope they show angular strata of calcareous spar. 



Height 23 millim., breadth 26 millim. 



This species has been found in many specimens in the shale of Wisby, but espe- 

 cially in the upperraost limestone beds of Sandarfve kulle, Klinteberg and Lilla Carlsö. 

 There are specimens from Länsa in Fårö and from Follingbo, more largesized and with 

 lower, blunt spire, which possibly may belong to this species, but the surface is too 

 corroded to show any sculpture and the aperture is obscured. 



Specimens sent from Mr S. A. Miller in Cincinnati as Strophostylus cyclostoraa 

 agree perfectly as to the ornamentation, but I cannot find the form of the aperture 

 in them. 



4. Platyceras disciforme n, 



Pl. II figs. 73—78, pl. XIX fig. 5. 



Shell discshaped or flat; whorls three and a half or four, the last free and without 

 any connection with the others. The dorsal or exteriör part of the whorls is thin and 

 almost sharpedged, the opposite part being much higher. The spire of the three con- 

 nected whorls is low and not visible above the other shell. The last whorl is enor- 

 mously large, widening at the point where it becoraes free, from 7 millim. to 28 mil- 

 lim, at the aperture. The aperture is of a shape between elliptic and triangulär, nar- 

 row at its exteriör lip, then widening and at highest near the median line, the inte- 

 riör lip so much reflexed as to touch the back of the spire. The surface is wrinkled 

 by transverse undulating lines of growth which are bent forwards toward the aperture 

 more at the dorsal side than at the opposite. There are moreover delicate, longitu- 

 dinal, threadtine striaa somewhat wavy and interrupted where they are crossed by the 

 transverse lines. 



Height at the columellar side of the aperture 15 milL, breadth 39 millim. In all 

 six specimens have been found in the sandstone of Hoburg, and a few also in the su- 

 perjacent limestone of Nackshejd and Klef in Wamlingbo and Sundre. 



