MANTELLICERATIDA. 105 
BaRROISICERAS DESMOULINSI Grossouvre. 
Barroisiceras haberfellneri: var. desmoulinsi Grossouvre, 1893, Ammonites Craie 
supérieure, pl. 2, fig. 6. 
A very stout form, with huge nodes and having the continuous keel 
until a later stage. 
Locality: Near Périgueux (Dordogne). 
Age: Coniacian. 
BaRROISICERAS HAUERI n. sp. Hyatt. 
Barroisiceras haberfellneri var. Grossouvre, 1893, Ammonites Craie supérieure, 
pl. 2, fig. 1 only. 
This is more compressed than B. desmoulinsi, the nodes are smaller and 
more numerous at the same age, and the keel is broken up into tubercles. 
Locality: Same as above. 
Age: Same as above. 
MANTEHLLICHRATIDA. 
MANTELLICERATID-. 
This group was described in Zittel’s Text-book, Cephalopoda, page 
587, as the Pedioceratide, and included only the genera Pedioceras, Douvil- 
leiceras, Stewroceras (Odontoceras) Cossmann, and Diadochoceras. Ot these, 
Steuroceras should be removed to the Hoplitide. In the young, or 
throughout life in primitive forms, there is close parallelism with Phri- 
codoceras and other discoidal tuberculated forms of the Cosmoceratidee, but 
in later stages the large single or imperfectly bifurcated costz cross the 
venter. All traces of tubercles may be lost at this or a later age in some 
forms, but in most species there are at least two rows, one on each of the 
ventro-lateral angles. There is never at any stage a row of median ventran 
tubercles nor a keel,“ nor are the ventral costz ever cut through by a 
narrow ventral channel, as in Hoplitidee. 
© Acompsoceras appears to be an exception in the figure given by Schluter, but that author distinctly 
states that no true keel is formed. 
