BELLEROPHONTID-iE. 323 



BucANiA, Hall, 184t. 



Syn. — Phragmostoma, Hall, 1862. Centrotheca, Salter. 



Shell planorbiform, the whorls exposed equally above and 

 below, with revolving stride ; last whorl much enlarged at the 

 aperture. Silur., Carb. B. expansa, Hall (Ixxxii, 100, 1). 



BUCANELLA, Meek. Shell without slit-band. 



TROPiDODiscus, Meek. Strongly compressed, disciform, widely 

 umbilicated, with a high keel and very short incision in the outer 

 lip ; callosity on the inner lip very little developed. Silur., Carb. 

 B. curvilineata^ Conr. (Ixxxii, 2, 3). 



TREMANOTUS, Hall, 1864. (Salpingostoma, Roemer, 1876.) Like 

 Bucania, but in place of the slit-band, a row of oval openings on 

 the last whorl. Mouth strongly expanded. Silurian. T. alpheus, 

 Hall. 



TUBiNA, Barrande, 1868. Like Tremanotus, but with three 

 rows of openings instead of one, on which long hollow tubes are 

 placed. Mouth very little expanded. Silurian ; Bohemia. 



EUPHEMUS, M'Coy, 1844. IJmbilicus absent or small, shell 

 with spiral folds, not continued on the last whorl, aperture 

 slightly contracted, lip sometimes emarginate, no distinct slit- 

 band. Carb. ; Grt. Brit., Salt Range, India. B. (Euphemus) 

 Indicus, Waagen (Ixxxii, 4). 



TROPiDOCYCLUS, Koninck, 1882. T. curvilineatus^ Conr. 



STACHELLA, Waagcn, 1880. More or less globular, smooth, 

 unsymmetrical, mostly umbilicated on one side and with a closed 

 umbilicus on the other ; slit-band distinct, but superficial, slit 

 shallow. Fossil. Salt Range, India. B. bifrons, Waagen 

 (Ixxxii, 5, 6). 



PHRAGMOSTOMA, Hall, 1861. Mouth much expanded, with the 

 slit forming a sinus ; slit-band well marked ; inner lip expanded 

 into a septum. Devon. ; New York. Is very closely related to 

 Carinaropsis, Hall. 



Bellerophina, d'Orb. 



Distr. — Cretaceous; Europe. B. Vibrayi, d'Orh. (Ixxxii, t). 



Shell subsymmetrical, globular, the whorls embracing as in 

 Bellerophon, but without sinus ; sides slightly unequal, the spire- 

 whorls perceptible above, while below the umbilicus is very 

 narrow. 



Carinaropsis, Hall. 



Distr. — Fossil, 2 sp. Silurian; America.- G. carinata, Hall. 



Shell having a patelloid aspect. Spire usually attenuated ; 

 body-whorl expanded abruptly ; cavity shallow, presenting a 

 kind of septum as in Crepidula. 



Cyrtolites, Conrad. 

 • Etym. — Kurtos, curved, lithos, stone. 



Distr. — Fossil, 13 sp. L. Silur. — , Carb.; JST. Am., Eur. C. 

 ornatus, Conrad. 



