182 G. LINDSTKOM, ON THE SILURIAN GASTKOPODA AND PTEROPODA OF GOTLAND. 



This is a well characterized genus with its peculiarly framed lips and lamellar 

 ornaments of the shell. I have placed this genus with the Turbinidte in consequence 

 of the congruence of its shell with several of the Liotidae of which group there are 

 some representatives not only recent and tertiary, but also in secondary strata. What 

 Stoliczka says')- of Liotia is wholly applicable to the Gotlandic fossils in question. 

 He says: ))The Liotidaj are usually of small size, sub-orbicular, with short spire, trans- 

 versally and spirally ribbed, often umbilicated, with the aperture circular, having more 

 or less thickened and continuous margins)). In the figure of Liotia Gervillei, given by 

 S. P. Woodward^), there is seen an acuminated spur projecting from the lower or 

 median edge of the inner lip quite as in ours. Strange enough no similar shells seem 

 to have been hitherto found in the Devonian and the Carboniferous Formations, as I 

 cannot find anj' mention made of such in the works of Goldfuss, Sandberger and 

 De Koninck. 



D'Orbigny^) has described and figured a »Delphinula reflexilabrum», which comes 

 very near to our genus through its »bouche ronde, avec un bord fortement epaissi, 

 et reflechi en un large peristome tranchant». It is derived from the Middle Lias of 

 France. 



In the Upper Silurian of Gotland I have found six species and in the Lower 

 Silurian hitherto not a single one has been discovered. 



I. Craspedostoma spinulosum n. 



PI. Ill fig. 32—34. 



Shell globular, naticoid, last whorl several times as large as all the others. Whorls 

 four, of which three form the short spire. Suture shallow. The surface is richlj^ or- 

 namented by transverse ribs,' situated at regular distances and there provided with 

 blunt spines. These spines, being regularly distantiated, form rows which also conti- 

 nue on the reflexed outside of the lip and give its extreme edge a serrated outline. 

 The aperture is ovate, inferiorly somewhat more narrow. The outer lip with a broad 

 border forming an expansion at right angle to the outside of the last whorl, projec- 

 ting above it to the length of two millimetres. It is evident that there has been a 

 spur or processus on the interior, upper edge, and probably also beneath the inferior 

 corner of the aperture but both have been broken. It is imbricated by the wavy lines 

 of former lips, resting in their place, while the aperture has been more constricted. 

 The inner lip is straight, bifid, thin and smooth, but does not cover the narrow and 

 deep umbilicus. H. 14 millim., br. 15 millim., length of aperture outside the lip 13 

 millim., inside 7 millim. 



From the limestone of Hoburg, between the oolite and crinoidal limestone strata, 

 where I found one specimen. 



') Palaeont. Indica, Gasteropoda of the Cretac. Eocks, 351. 



2) Manual of Shells, pi. 10 f. 14. 



') Paleont. Fran?. Terr, jurassicjues, 317, pi. 323 f. 14—16. 



