KONGL. SV. VET. AKADEMIENÖ HANDL. BAND. 19. N:0 6. 59 



oldest Ga«tropod knowu in Sweden is Metoptoma Barrandei LinnaksöON from the Cam- 

 briari strata of Scania, in the lower portion of the zone of Paradoxides Tessini. 



Palseacmsea? solarium n. 



Pl. XIX lig. 3, 4. 



Shell patelliforni, regularly acuniinate, apex nearly median or slightly anterior, 

 the outline oblongate from above. Outside of the shell smooth, only eoncentrically 

 vvrinkled at regular distances by larger elevated ridges, the interstices between them 

 being finely striated by parallel lines. Interiorly there is around the apex a narrow 

 circle of detached muscuUir scars, visible on the nncleus as delineated in the figure. 

 Height 3 millims., length 6 mm., breadth 4 mm. 



Hitherto tvvo specimens have been found in the red, conchiferous limestone of 

 Sandarfve knlle. 



Fam. IV. CALYPTRJj]IDiE Broderip. 



Gen. PLÄTYCERÄS ComAD. 



1809 Uelicites Martin Petref. Derbyeusia, pl. 40 fig. 43. 



1810 Capulus MoNTFOET Concli. System. II, 54; though not intoiided by him for fossil species, it was 



adoptetl for suoli by De Koninck Anira. Foss. de Belgique, 331. 



1812 Pileopsis Lamarck adopted by Sowerby Min. Conchol. vol. VI pl. 607, 223. 



1823 Aetita Fischer von Waldheim Mera. Soc. Imp. Naturalistes de Moscou VI, 234. 



1828 Turbinites Hisinger Anteckningar IV, 221. 



1840 PhUyceras Conrad Ann. Rep. Geol. Surv. N. York, 205. 



1841 Åcrotiidia (rectius Acrocylia) Phillips Pal. Pösa. of Cornwall, 93. 



1842 Platyostoma (rectius Platystoma) Conrad Journ. Acad. Nat. So. Pliilad., 275. 



1843 Orthomjchia Hall Eept. 4tli Distr. N. York Geol. Survey, 172. 



1844 Naticopsis Mac Coy p. p. Synops. Carb. Poss. Ireland, 33. 

 1859 Strophostylus Hall 12th llept. State Cab. N. York, 20. 

 1859 Igoceras Hall Pal. N. York vol. III, 330. 



1868 Exogyroceras Meek & Wortuen Geol. Survey Illinois, vol. III, 508. 

 1878 öapreolus R. Etheridge Sr. (lapsu!) Qu. Journ. Geol. Soc., vol 34, 603. 



Shell globose or naticiform loith sinall, depressed or only moderateli/ iirominent 

 spire, last whorl enormously developed, globose or transversally protracted and elongated. 

 Aperture circular or oval^ outer lip reflected and enlarged into a thin laminar edge, ivhich 

 in well preserved specimens is persistent during the continued groivth of the shell and gives 

 the exteriör surface a characteristic ornamentation of projecting, thin laminai. The inner 

 lip of the aperture much varying ; sometimes with twisted {>^Strophostylus>->), sometimes thin 

 and smooth columella {^iFlatycerasf). No opercidum has ever been found. 



In justiiication of the above list of synonymous genera the foUowing statements 

 of the opinions of various authors upon this matter may be adduced. The earliest 

 description of any fossil belonging to this group is in Martins Petrificata Derbyensia 



