136 <T. LINDSTRÖM, ON TIIE SILURIAN GASTROPODA AND PTEROPODA OF GOTLAND. 



are Silurian, have a slit in the lower edge of the exteriör lip, much more shallow than 

 tliat of the Pleiirotoinaridie and nearly alike that in Pleurotoma and also in Turritella^). 

 Dnring the growth this slit is never changed into a real slit band as in the Pleuroto- 

 maridaj, at the highest there is a narrow ridge, where the lines of growth are curved 

 backwards. When we see how raollusca, in other respects dissiinilar, are provided with 

 this slit in their shell, it is indeed very questionable whether the Loxoneraata only on 

 that ground are so nearlj' related to the genus Enomphalus as to be included in the 

 same faniily as here proposed. There may, however, be added the siinilarity in the 

 Consolidated apex, and the)' may thus, at least provisionally, be regarded as related 

 and Loxonema in a certain way to hold the same position to Enomphalus as Murchi- 

 sonia holds to Pleurotomaria. 



Gen. EUOWIPHäLUS Sowerby p. p. 



1814 Enomphalus Sow. p. p. Mineral Conoli. I, 97. 



1833 Bifrontia Desiiayes p. p. Descr. Coqu. foss. des environs de Paris, 221. 



1835 Schizostoma Bronn Letbsea Geogn. Ed. 1, 95. 



1843 EccyliomjjJialus Poktlock p. p. Report Geol. of Londonderry, 411. 



Shell discoid loith contiguous or disjointed wliorls; on the apical sideoftlieaferture 

 a shallow and obtuse slit or sinus is situated, the traces of which are seen on the lohorls 

 as a more or less elevated ridge, towards which the lines of growth are turning their api- 

 cal angle. The apex of the shell is fdled ivith a solid calcareons depiosition of organic 

 origin and is often subdivided through transverse diaphragms. 



After the detailed expositions of the affinities of this genus as given by De Ko- 

 NiNCK in his latest grand work and by Stoliczka^), Waagen^) and Etheridge jr*) only 

 a few remarks need be added, chiefly to show the standing point in this question of 

 J. Sowerby and Deshayes, the conchologists who have most essentially influenced the 

 opinion of others. 



When James Sowerby in February 1814 published his new genus Enomphalus 

 in J^ IX of the Mineral Conchology p. 97, he founded it on such species as Euomph. 

 pentangulatus, catillus and nodosus, all provided with the small notch in the corner of 

 the aperture on the apical side and a ridge in connection with it on the surface of the 

 whoi'ls. But already in April the same year he joined with them in that very genus 

 others as E. discors, rugosus etc, which do not share in the peculiarity of conforma- 

 tion, distinctive of the former. Consequently, when we are to fix the characters of 

 Euomphalus it must be in the original conception of its author. Next, the opinions of 

 Deshayes are of great importance, as most of the subsequent authors seeni to have fol- 

 lowed him. In 1830'') he did not accept Euomphalus as an independent genus, but 



') BooGE Watson MoUnsca of the Challenger Exp. in Jonrn. Linn. Soe,, Zoology, vol. 15, p. 220. 



-) Palreontologia Indien V, p. 247. 



3) Pal. Ind. XIII p. 86. 



^) Ann. mag. N. H. 5th-Ser. vol. 5, p. 480. 



5) Eneycl. Method., Hist. Nat. d. Vers, vol. II p. 162. 



