CEPHALOPODA. 197 
BAcTRITES, Sandberger (=stenoceras, D’Orbigny ?). 
Shell straight ; sutures lobed. 
Type, B. subconicus, Sbger. 
Distribution, 3 species. Devonian, Germany. 
CERATITES, De Haan. 
Type, C. nodosus (Pl. III., Fig. 2). 
Shell discoidal; sutures lobed, the lobes crenulated (Fig. 61). 
Distribution, 29 species. Deyonian—Chalk. Europe, India. | 
M. D’Orbigny describes five shells from the gault and Upper 
greensand as ceratites ; but many ammonites have equally simple 
sutures, when young. 
Fig, 62.4 
AMMONITES, Bruguiere. 
Etymology, ammon, a name of Jupiter, worshipped in Libya 
under the form of a ram. The ammonite is the cornu ammonis of 
old authors. 
Synonyms, Orbulites, Lam. Planulites, Montf. 
Shell discoidal ; inner whorls more or less concealed; septa 
undulated; sutures lobed and foliated ; siphuncle dorsal. 
* Fig. 61. Suture of ceratites nodosus (Brug). The arrow in the dorsal lobe points 
towards the aperture. 
1 Fig. 62. Ammonites rostratus (Sby.) From the U. greensand of Devizes, in the 
cabinet of W. Cunnington, Esq. 4, front view of one of its partitions. 
