254 



THE LIAS AMMONITES. 



Oolite of France and England we find Ancyloceras annulatum, d'Orb. ; in Germany 

 Ancyl. baculatum, Quenst. ; and in the Kelloway Rock of England we have a third species, 

 Ancyl. Calloviense, Morr. It is in the Cretaceous rocks where this genus attains its chief 



Fig. 166. — Jncyloceras Malheronianum, d'Orb. 



development. Ancyloceras Mather onianmi, d'Orb. (fig. 166), is from the Upper Neocomian, 

 and Ancyloceras Puzosianmn, d'Orb. (fig. 167j, is from the Lower Neocomian. 



Fig. 167. — Ancyloceras Puzosiaimm, d'Orb. 



Genus Baculina, d'Orbiyny. — Shell straight, with a surface destitute of ornamenta- 

 tion. BacuUna resembles Baculites except in the lateral lobes being single-pointed. 



Genus Perisphinctes, Waay. — Shell in general discoidal, with a wide umbiHcus and 

 a round ventral edge. The sculpture consists of straight or oblique ribs, inclined forward, 



Fig. 168. — Perisphinctes Martinsii, d'Orb. 



in general polytomate (much divided), and without tubercles. Mouth-border simple or 

 with auricles ; a circular contraction visible on the shell near the outlet at certain stages of 



