CEF HALOPODA. 
Shell with the produced portion very short or wanting. 
This sub-genus bears the same relation to Litwunculus (the 
existence of which is supposed) that Ophidioceras does to 
Litwites. 
Distribution, 8 species. Middle Silurian. Russia, Germany, 
Norway. 
HERCOCERAS, Barrande, 1867. 
Htymology, erkos, a wall, and ceras. 
T'ype, H. mirum, Bar. Middle Silurian, Bohemia. 
Shell usually involute, as in Nautilus, rarely with separated 
whorls as in Gyroceras, or with a spire as in T'rochoceras. Body- 
chamber with a diaphragm perpendicular to the axis of the shell, 
the concavity of which is opposed to that of the last septum. 
This disposition throws the aperture on the convex side of the 
shell, which is deeply excavated. Siphuncie dorsal, cylindrical, 
inflated between the chambers, separated from the shell. 
Nautilus subtuberculatus, Sandberger, from the Devonian of 
Nassau, may belong to this genus. 
~ 
BATHMOCERAS, Barrande, 1867. ? 
Etymology, in allusion to the imbricated arrangement of the 
partitions. 
Type, B. complexum, Barr. (Orthoceras). 
Shell haying the general appearance of Orthoceras. Part of 
the body-chamber occupied by a series of imbricating plates, 
which decrease in horizontal extension from below upwards. 
Siphuncle composed of a series of superimposed funnel-shaped 
tubes, the narrow end directed towards the aperture of the shell. 
Distribution, 2 species. Middle Silurian, Bohemia. 
AULACOCERAS, Hauer, 1860. 
Htymology, aulax, a furrow, and ceras. 
Type, A. sulcatum, Hauer, Fig. 7. 
Shell straight, like Orthoceras ; corrugated, 
with two deep lateral furrows; siphon simple, 
very small, marginal and dorsal, situated ¢ 
between the longitudinal sulci. The test 
increases rapidly in thickness towards the 
apex of the shell. 
The genus is a transition form between 
Fig. 7. Transverse seo 
the Nautilide and the Belemnitide. tian of Ante 
Distribution, 4 species. Upper Trias, catum, 
Austria. 
B3 9 
