138 G. LINDSTROM, ON THE SILURIAN GASTROPODA AND PTEROPODA OF GOTLAND. 



as Schizostoma Pusozii and Sch. radiatum, which are of a type entirely different from 

 E. catillus. 



To sum up the chief results now gained, I believe: 



l:o) that Euomphalus is to be maintained in the sense which Sowerby at first 

 gave it. 



2:o) that Straparolus, as well as Oriostoma must be removed from Euomphalus 

 as not identical with it and belonging to different families, Oriostoma being one of 

 the Turbinidaj. 



3:o) that of the Silurian shells Euomphalus along with Loxonema must be re- 

 garded as members of the family of the Euomphalidte De Kon. p. p. and 



4:o) that this is to have its systematic place next to the Pleurotomaridse, as there 

 are forms linking both together. 



Eccyliomphalus, the only remaining synonymic genus, the identity of which 

 with Phanerotinus is doubtful, comprised, when first established, two species and the 

 author, Portlock, lays stress on »its great resemblance to an unrolled Euomphalus». 

 And, in fact, these species come near to such as our E. Gotlandicus and E. triquetrus. 

 But by and by quite different shells were introduced into it. Eccyl. alatus Ferd. Roe- 

 MER, concerning which species see above at page 110, is an instance of the adventitious 

 forms. This genus has thus come to contain species of evolute Euomphali and like- 

 wise evolute Pleurotomaria3. It must, consequently, be broken up, and its species be 

 distributed in these genera. Both the typical species are Euomphali. 



The genus Euomphalus has a wide geological range. In Sweden the oldest spe- 

 cimens have been found as deep down in the Lower Silurian as in the Lower Gray 

 Orthoceratite limestone of Dalecarlia, from where the specimen, delineated on pi. XllI 

 fig. 36 — 38 has been derived. It is evolute, with three widely separated whorls of cir- 

 cular section, the aperture angulated in its lowest corner, where the large and distinct 

 slit, fig. 36, is situated. The ridge in continuation of this runs very sharp along the 

 whole apical side of the whorls. The ornamentation consists of imbricated, transverse 

 striaj, curved back in an acute angle, where they cross the apical ridge. The oldest 

 whorls on the visible part of the apex is divided in chambers through at least four 

 transverse diaphragmata. I have named this interesting species Euomphalus Angelini 

 in remembrance of the indefatigable and gifted man. Professor N. P. Angelin who devo- 

 ted his life to the investigation and elucidation of the palaeontology of Scandinavia. 



Next in order of time we find a Euomph. obtusangulus ') which resembles the 

 Upper Silurian E. Walmstedti and E. prsBCursor, in the Leptjena limestone of Dalecar- 

 lia. In the Upper Silurian of Gotland there are five species, besides fragments indica- 

 ting others. It is well known that there have been several species found both in the 

 Devonian and Carboniferous formations expecially in the later, where the genus seems 

 to have attained its culmen. Whether the Euomphali had continued during the Meso- 

 zoic times is uncertain. They have, it is true, been recorded as occurring in the Tri- 

 assic Rocks of Austria"). But the form of these presumed Euomphali does, certainly 



') Angelin & Lindstrom. Fragmenta Silurica p. 12 pi. XVII f. 19 — 20. 

 -) See the works of Klipstein and Lacbe. 



