70 G. LlNDSTliOM, ON TlIK SILUh'IAN GASTKOl'OUA AND I'TEliOl'ODA OF GOTLAND. 



nucd (jrowlh a dit Ixmd, which assuines the ahcqjc of an elevated keel or also a sunk, 

 shalloio groove; its inferior jiiarf/in covering a part of the hack of the preceding volution. 



Table of tlie genera: 



A) Slit band entire, continuous without any openings. 



1. Shell globular, involute, apurtural lips wide, trumpet shaped. Slit band 

 broad, sunk. 



Belleropliou Montfort. 



2. Shell diseiforuj, laterally compressed, aperture hastate, whox'ls in several species 

 not involute, free and not contiguous. Slit band elevated, often forming a sharpedged keel. 



Oyrtolites Conrad') 



B) Slit band always elevated, perforated by a series of oblong openings- Aper- 

 ture many times wider than the volutions, ornauienlul lines spiral. Shell discoid, in- 

 volute. 



Tremanotus Hall. 



As to the systematic place of this family every one conversant with the conclio- 

 logical literature is aware that there are few pal;\)ozoic genera on which the opinions 

 of the authors have been more divided and differed more widely. For a succinct sur- 

 vey of these varying opinions it is enough to refer to the works of De Koninck"), Meek'^) 

 and Waagen *), where a relation is given in full. Bellerophon has been ])laced amongst 

 the Cephalopoda by its first discoverer Hupsch, by its denominator Montfort, by De 

 France, Mac Coy, Phillips, Portlock and Cuenu. It has been considered as one of 

 the Heteropoda by Sowerby, D'Orbigny, Bronn, Desiiayes, D'Archiac and Verneuil'') 

 PniLLiPi"), EiciiwALD, Owen'), Salter, Woodward**) and Adams. It has been numbered 

 amongst the Gastropoda by Blainville and Valenciennes (as related to Accra and 

 Bulla), Fleming (as Aetieon), De Koninck and Pictet (to Emarginula "corame un lien 

 perdu entre les Emai-ginules et les Pleurotomaires"), James Hall, Sandberger, (joining 

 them with Pleurotomaria through Porcellia), Meek and Woktiien. Among the most 

 recent authors Stoliczka") hesitates between placing Bellerophon in the Heteropo- 

 da, Opisthobranchiata and Cephalopoda. Iiieuing'") denies the affinity of the Bel- 

 lerophons to the recent Heteroi)oda and places them in a family of their own, quite 



') xV new generic type, intermediate between Belleroplioii and ('yrtolitcs is probaljjy rornied by the ^^ti- 



cies named B. norvegicus by Bkoggeu in his »Silnriseiien Utagen", p. .53. 

 -) AiiimuLix i'ossiles de la Belgicpio p. 334. 



^) On tlu; al'linities of the BeUerophontidii; in I'roc. Chicago Ac. Se. Vol. 1, p. 9. 

 ••) I'aheontol. Indica. Ser. XIII p. 126. 

 ■') Geol. Transactions vol. VI, p. 325. 

 '■) Handbuch der Malacol. p. 28.5. 

 ') Palix;ontology p. 72. 

 ^) Manual of Shells p. 201 to Atlantidic, but in the Supplement edited by K. T.\Ti': in 186!^ it is placed 



as a subfamily to the Plcurotomariic amongst the lIaliotida\ 

 ") Pahcontologia Indica. V. Gastrop. p. 3t)3. 

 '") Ncrveiisyst. der MoUusken p. 143. 



