72 G. LINDSTRÖM, ON TlIE SILURIAN GASTROPODA AND PTEROPODA OF GOTLAND. 



Gen. BELLEROPHON Montfort. 



Syn. 1781 Nautilites HiJpscn p. p. Naturgeschiclite des Niedenleutsclil. I, 23, pl. III f. 20 — 2.3. 

 1808 Belleropli.on MoNTroRT Couchyl. Systematique, I, 50, 51. 

 1812 ElUpsolithes Sowerby p. p. (iion Montf.) Min. Conch. vol. 1, 81. 

 1825 Bellcroplms Blainville (»mala einendatio» Hermansen) Man. de Concliyliologio, 4. 

 1847 Biiccmia Hall p. p. Pal. N. Y. vol. 1, 32. 

 1847 Carinaropsis Hall p. p. Pal. N. Y. vol. 1, 183. 



1849 Vasulites Hermansen (non Montf.) Ind. Gen. Malao. Primordia II, G77. Sco bclow. 

 1861 Phratjmostoma Hall 14 Rep. N. Y. State Cab., 94. 



1882 Waagenia De Koninck Notice sur la famille des Bellerophontidiic, Ann. Soc. Géol. de BelgiquelX, 14. 



This name being already given away by Neumayr it vvas clianged by De Koninck iiito the fol- 

 lowin^. 



1883 Waagenella De Koninck Faune Carbonif. Belg. II pt. IV. Explic. des planches, pl. 38. 



Shell globose, involute, ivith the whorls in the same plan or nearly so, concave on 

 the umhilical side as well as on the apical one, so that no distinction can be made hetioeen 

 them. Aperture circular or oval, suddenly much enlarged, lips thin, continuous, interiör or 

 columellar lip covering the hack of the second convolution. The slit hand is always distinct, 

 originating from a deep notch in the middle of the exteriör lip; it is in several species 

 m,uch varying, heing elevaied as a keel on the last convolution, sunk as a channel or a flat 

 hand ioiver down on the older whorls. It is covered. with quite the same sort of semilu- 

 nar, backwctrds curved wavelets as are seen in all Pleiirotomaricc. The umhilicus is in 

 the small specimens very large and opeti and is in the older ones covered and hidden he- 

 neath the reflexed margiti of the aperture. In some, hoivever, it continues uncovered or 

 open. The exteriör ornamentation of the shell consists of transverse strice, which often are 

 crossed hy longitudinal ones. Moreover there is a pecidiar feature, ohserved in Gotland 

 specimens, consisting in a series of thin laminui, which are nothing hut the continuation of 

 the lines of growth. They are gently curved outioards and are most crowded and per- 

 fect in the umhilical tube, where they have also heen hest protected against fracture. These 

 lamince may as in Tremanotus, each in its tum, have formed the successive aj^ertures and 

 then heen partly absorbed, partly abraded 'and only preserved where they were protected. 



In explanation of the synonyms given above the following remarks may serve. 

 Ellipsolithes Sow. in Mineral Conchology, vol. I pp. 81, 83, 84 is not to be confounded 

 with Montforts genus of the same name which only contains Polythalamia. That of 

 SowERiJY consists of one species of Nautilus, one of Goniatites, and one of Bellerophon 

 (B. ovatns) according to his own eraendation in Min. Conch. vol. 5 p. 107. But Mor- 

 ris, Cat. Brit. Foss. p. 302, regards them all as Cephalopods. Bucania Hall Pal. 

 N. York vol. 1 p. 32 is chiefly distinguished therebj^ that the aperture is dorsally 

 abruptly expanded and that the volutions are all visible in the umbilicns. In the 

 fourth volume of Pal. N. York Hall seems to have abandoned his opinion on the di- 

 stinction of this genus and includes it amongst the Bellerophons. The wide aperture 

 is moreover coramon with most of the Bellerophons and as to the uncovered and 

 large umbilicus Deshayes remarks in the Journal de Conchyliologie vol. I p. 205 

 »rexistence de Torabilic est un caractére indifférent», and not of importance enough to 



