AMMONITIDA. 87 
septate part, but not curving over the aperture. B. incurvatus, 
Dujardin. 
cyRTOCHILUS, Meck, 1876. Shell straight; aperture opening 
towards the antisiphonal side, and the lateral sinuses of the lip 
excavated in the opposite direction ; projection of siphonal margin 
of lip abruptly arching over the aperture, and the antisiphonal 
margin of same deeply sinuous instead of convex in outline; 
interior with regularly disposed ridges, leaving oblique constric- 
tions on internal casts. Hamites baculoides, Mantell = B. obli- 
quatus, Sowb. 
BAcuLina, d’Orb., 1847. 
Distr.—2 sp. Jurassic, Lower Chalk; Europe. B. arcuaria, 
Quenstedt (xxxii, 24), 
Shell straight, point conical; sutures of septa arow of rounded 
lobes, toothed at base. 
