12 ART. 2.— H. YABE : CRETACEOUS 



The inner volutions, which gradually broaden anteriorly, are 

 nearly round in section, showing only a slight lateral compression. 

 The body-chamber is longer than one half of the last volution ; 

 it is high and narrow. Umbilicus moderate in size ; relatively 

 narrower on the last volution than on the inner. 



The surface of the septate portion is apparently smooth while 

 the-body chamber shows radial farrows which are 15 in number ; 

 the furrows are shallow and not well defined, becoming gradually 

 obsolete toward the umbilicus. The interspaces are flat, slightly 

 elevated, broadest along the ventral side, measuring 1.5 — 2.5 cm. 

 in breadth. These flat interspaces and furrows extend also over 

 the ventral surface. 



The suture line which is partly preserved, shows a lanceolate 

 siphonal saddle with serrated margin. The external saddle is 

 inclined inward and asymmetrically bitid, while the first lateral 

 lobe is broad and deep. 



The suture line and the appearance of the septate portion of 

 this species remind us of an Ammonite of the group of Lyioceras 

 fimbi'ialum Sow. sp., while the suddenly enlarged and laterally 

 compressed body-whorl, together with its peculiar sculpture, 

 distinguishes it from all the known allies. 



Locality : — A clift' somewhat above the lowest gorge of the 

 Ikushumbets, Prov. Ishikari, where the species occurs together 

 with Puzosia subcorbarlca m. 



Horizon : — Lower Ammonite- beds. 



