210 
Neocomian, and Ancylcoeras Puzosianum, D’ORB., is from the 
Lower Neocomian, (fig. 69). 
A NWI 
Fia. 69.—Ancyloceras Puzosianum, d’Orb. 
Genus Bacutina, d@’Orbigny. 
Genus PerispHinctes, Waag.—Shell in general discoidal, with 
a wide umbilicus and a round ventral side. The scuplture 
consists of straight or oblique, forward directed ribs, in 
Fic. 70.—Perisphinctes Martinsti, d’Orb. 
general polytomate, and without tubercles. Mouth-border 
simple or with auricles, and a circular contraction visible on 
the shell, near the outlet, at certain intervals of growth. Body- 
chamber from two thirds to an entire whorl. Lobes similar 
to those in Stephanoceras, differing, however, in being more 
ramified, and having pendant columellar lobes. Aptychus 
bivalved, calcareous, very thin, and externally granular. Per- 
sphinctes Martinsit, p’Ors, fig. 70, from the Inferior Oolite of 
France and England, is geologically the oldest of this group, 
which is largely developed in the Middle and Upper Jurassic 
strata of Europe, and a few species are found in the chalk. 
a 
