CEPHALOPODA FROM THE HOKKAIDO. Z/ 



row of tubercles bordering the umbilicus. Kibs round, simple 

 and uniform, separated by intervals of like breadth, gently 

 curving forward on the ventral surface of the whorl and 

 generally bearing a moderately sized tubercle on the umbilical 

 margin, umbilical wall perpendicular and smooth. 



The volution next to the outer one differs from it mainly 

 in having a relatively wider umbilicus. 



The siphonal saddle is broad and high, flat on the top, and 

 with a few denticles on both sides. The external and the first 

 lateral saddles are exceedingly high and simple, with a few short 

 branches, and are tripartite on the top. Each branch terminates 

 in a round lobule. The first lateral lobe is bifid and somewhat 

 shorter than the external one. 



As already mentioned, the present species is an ally of Amm. 

 superstes and Amm. rudra ; of these two, it exhibits a greater 

 resemblance to the first than to the second. However, it differs 

 from the first by its higher whorl bearing more numerous ribs 

 and tubercles. 



Locality : — The specimen was found in a nodule of marl, 

 obtained as a pebble in the YCibarigawa. This being the sole 

 example now at the writer's disposal, its stratigraphical position 

 cannot be given with an}' certainty. 



OLCOSTEPHANUS Neumayr. 



Neumayr^^ correctly remarked that an Ammonites from 

 Urakawa brought under the genus Stephanoceras by Brauns"^ 



1) Neumayr : Neues Jahrb. für Mineralog. Geolog, u. Palœontolog. 1881 Bd. II., p. 80. 



2) Brauns: Vorläufige Notiz über Vorkomnisse der Juraformation in Japan. 



