36 



AKT. 2. H. YABE : CKETACEOUS 



by a wider umbilicus and relatively low, mucli compressed wliurls. 

 Still tliere is no doubt that there exists an intimate relation 

 between these two forms. 



The Japanese species is very variable in its form ; some 

 (PI. v., fig. 2) show a wider umbilicus and lower whorls, 

 strongly reminding us of the form of G. iJolUissiinum, while 

 others are characterized by a narrower umbilicus, higher whorls 

 and the earlier appearance of broad ribs. The latter is now con- 

 sidered merely as a yariety (var. obscur a). Fig. 3 a, b. in PI. YI. 

 is a form intermediate between this and the normal type. 



Localities and Horizon : — The uj)per course of the Ikushum- 

 bets, above the mouth of the right branch, the Yoshiashizawa, 

 and along the latter itself; found in the u])per Ammonite-ljeds. 

 Along the Opiraushibets, Prov. Teshio, in the /Scaphites-hiida, 



GAUDRYCERAS YOKOYAMAI m. 



PI. VP, figs, la, b, 2 a, b; PI. YIP, fig. G'. 



There are only a few specimens belonging to this species, 

 one of which is a cast of an interior of a moderate size, showing 

 the suture line ; the others are smaller, but mostly provided Avith 

 the shell. 



P)imension : — 



iJianieter. 1.5 cm. 100. 



Height ol" the last whorl. 2.0 „ 44. 4.2 „ 4S. 



Breadth of the last whurl. 1.8 ,, 40. 40 „ 4C, 



Width oC mubilioiis. 1.35 „ 30. 2.1 „ 24. 



1) A young individual from the Yilbarigawa. 

 2} The largest specimen from tlie Ikushumbets 



(') Kan,,. 



S.G cm. 100. 



