308 Dr. T. Wright on the Strombidse of the Oolites, and 



from the ooUtic and cretaceous rocks appear to occupy a position 

 intermediate between these genera, and ought probably to be 

 separated into a distinct genus ; this in fact was suggested, and 

 the genus Rosti'otrema proposed, by Mr. Lycett, in a paper which 

 he read before our Society in August 1848, for the reasons that 

 the winged shells of the Oolite called RosteUaria diflPer from that 

 genus in " the absence of the upper or posterior siphon upon the 

 spire, the outer lip not extending beyond the body-whorl, or but 

 slightly upon the penultimate, and there being no corresponding 

 thickening upon the inner lip to form a channel." 



Our esteemed associate informs me that he has now cancelled 

 his former name and substituted Alaria for the reception of many 

 of the winged shells of the Great Oolite hitherto described as 

 RosteUaria. 



The winged shells discovered in the oolitic strata of Europe 

 belong to the genera Pteroceras, RosteUaria, Chenopus, and it 

 may not therefore be uninteresting to make a few remarks on 

 the fossil species of these genera. Goldfuss t and Miinster 

 figured and desci'ibed two species of Pteroceras, P. oceani and 

 P. conica, from the Kimmeridge and Portland stages of Germany, 

 and five species of RosteUaria, R. gracilis, R. subpunctata, R. se- 

 micarinata, R. tenuistria, and R. nodosa, from the lias, and two 

 species, R. bicarinata and R. spinosa, from the inferior oolite near 

 Pappenheim. 



Roemer J figured and described two species of RosteUaria, R. 

 costata and R. caudata, from the coral rag of Hanover. 



Koch and Dunker § described and figured one species of Che- 

 nopus, C. Philippi, from the inferior oolite, and two species, C. cin- 

 gulatus and C strombiformis, with RosteUaria nodifera, from the 

 middle oolites of North Germany. 



Prof. Deslongchamps || figured and described ten species from 

 the oolitic rocks of Calvados in Normandy, five of which, P. ves- 

 pertilio, P. ponti, P. sexcostata, P. musca, and P. incerta, are from 

 the Kimmeridge clay of Honfleur, and five, P. antractoides*, P. 

 vespa, P. balanus, P. retusa, and P. paradoxal, were obtained from 

 the great oolite of Ranville. This profound and accurate observer 

 found five species of RosteUaria in the lias and oolites of the 

 same region. R. trifida^ ranges from the upper lias to the Kim- 

 meridge clay ; R. hamus* is common to the inferior and the great 

 oolite ; R. myurus is found in the inferior, and R. hamulus^ and 

 R. cirrtis'^ in the great oolite of Ranville. 



t Petrefact. Germanife, tab. 169 and 170. 



X Versteinerungen des Oolitlien-Gebirges. 



§ Versteineiimgen des Nord-deutschen Oolith-gebildes. 



II Memoires de la Soci^te Linneenne de Norraandie. 



