4 
: 
209 
‘lobe often equals, but is sometimes shorter, than the principal 
lateral, which is large and branched; the second lateral is 
small, and there are several auxiliaries. The Aptychus is the 
same as in Stephanoceras. 
This genus appears first in the upper beds of the Inferior 
Oolite with Cosm. Parkinsoni, Sow., and Cosm. Garantianum, 
p’Ors. In the Kelloway Rock and Oxford Clay are several other 
species, as Cosm. Calloviense, Sow., Cosm. Duncani, Sow., fig. 65. 
Cosm. Kénigi, Sow., Cosm. Gowerianum, Sow., Cosm. Jason, Remn., 
fig. 67, Cosm. Julii, p’Ors., and in the chalk it is represented 
by Cosm. verrucoswm, D’ORB. 
Genus Ancytoceras, d’Orbig.—Shell spiral, rolled on the same 
plane, with few whorls, all of which are disjointed and separate 
from each other; the last projected outwards in a horizontal 
line, and then turned upwards and inwards, forming an arch 
opposed to the turns of the spire. The recurved portion without 
septa is the body-chamber. The mouth-border is simple, round, 
and thickened by a shelly inversion. The septa are transverse 
and symmetrical, divided into six lobes, which are very unequal 
in size, and formed of very ramified, elongated digitations. 
This genus first appeared in the Jurassic seas; in the Upper 
beds of the Inferior Oolite of France and England, we find 
Ancycloceras annulatum, v’Ors.; in Germany Ancyl. baculatum, 
Quenst.; and in the Kelloway Rock of England we have a 
third species, Ancyl. Calloviense, Morr. It is in the Creta- 
ceous rocks where this genus attains its chief development. 
xy), sit yy 
a 
Bs 
eS lig 
ES FZ 
=> = — 
eE i < 
Vom, “AT Wes 
Ze» 
i 
MG 
AMR L 
Fie. 68.—Ancyloceras Matheronianum, d’Orb. 
Ancyloceras Matheronianum, v’Oxs., (fig. 68,) is from the Upper 
