BITOMUS. 13 
opposed to apex, and would apply it to the anterior of the 
aperture. 
BA’TOLITES. Montf. Hrppurires, Auct. 
BELEMNITES. <Auct. (Bedenvov, belemnon,a dart or arrow.) 
Fam. Orthocerata, Bl. and Lam. JDescr. Straight, conical, 
consisting of two parts; external portion forming a thick, solid 
shield, with a cavity at the base, to admit the internal portion 
or nucleus, which is more mathematically conical, and is divided 
into chambers, by smooth, simple septa, perforated by a lateral 
siphon. Obs. These singular fossils have long attracted the 
attention of philosophers, as well as of the vulgar, from whom 
they have received the various curious appellations of Thunder- 
stones, Petrified Arrows, Petrified Fingers, Devil’s Fingers, 
Spectre Candles, &c. The above description includes the genera 
Hibolithes, Porodragus, Cetocis, Acamas, and Paclites, Montf. 
Actinocamax, Stokes. 
BELLER'OPHON. Montf. Descr. Convolute, symmetrical, um- 
bilicated, with a double dorsal ridge; aperture wide, semilunar. 
Obs. The general appearance of the two or three fossils com- 
posing this genus is like that of Nautilus, but not being cham- 
bered shells they approach very near to Argonauta, from which 
they differ only in the thickness of their shell, and in roundness 
of form. This genus is placed by Montfort among cham- 
bered shells, and by Blainville next to Bulla. It belongs to the 
Monothalamous Cephalopada of Lamarck. Fig. 486, 487, B. 
Tenuifasciata. 
BIAPHO'LIUS. Leach. Supposed to be identical with Hiatella. 
BIFID. Divided, double. 
BIFRON’TIA. Desh. Also Omataxits, Desh. Fam. Turbina- 
cea, Lam. WDescr. Discoidal, planorbicular, with whorls some- 
times disunited ; umbilicus deep, keeled at the margin; aperture 
longitudinal, subtriangular, somewhat dilated; outer lip acute, 
separated by a deep notch at both extremities. Obs. We do not 
see any reason for separating this genus from Soiarium, 
except in the last mentioned character. The few fossil 
species which this genus contains (Solarium disjunctum, 
Bifrons,&c.) are found principally in the Paris Bason. Fig. 354, 
Solarium Bifrons. 
BIGENERINA. D’Orb. A genus of microsopic Foraminifera. 
BIROSTRITES. Lam. (Beak.) A fossil formerly considered 
as a bivalve shell with conical umbones, and placed in the family 
of Rudistes, by Lamarck; but now known to be an internal 
cast of Spheerulites. 
BISIPHY’TES. Montf. Described by him as like a Nautilus, 
but having two distinct siphons. Nosuch fossil is now known 
to Naturalists. ° 
BI'TOMUS. Montf. <A microsopic shell, deriving this generic 
appellation, from the appearance of a double aperture. 
a Vee ee | oth brralie 
