CEPHALOrODA FROM THE HOKKAIDO. 21 



At fii'st the shell forms a more or less flat spiral coil wound 

 siiiistrally îis in Helicoceras, its diameter being about 2.7 cm. 

 and the cross-section of the whorl at the end of the second vo- 

 lution about 0.9 cm. The further growth is no longer spiral, 1)ut 

 it consists in turning to the right and then to the left several 

 times and thus forming many U-shaped curves which cover the 

 first part of the shell from six directions, so that the plane of 

 the curves roughly corresponds to the six sides of a cube. The 

 limbs of each single curve and of those adjacent come nearly in 

 contact. 



In cross-section, the whorls of the younger, spiral portion 

 are nearly round, while those of the older are somewhat oblong, 

 the dorso-ventral diameter being a little narrower than the 

 lateral one. The body chamber is probably long, as about two 

 anterior curves seem not to be septated. 



As our shell consists of several U-shaped curves, wdien it is 

 compared with the ordinary Turrilites, one limb of a curve corre- 

 sponds to a whorl of a sinistrally w^ound Turrilites, and the 

 other to that of a dextrally wound one. 



The ribs are simple, smooth and uniform (except at the 

 anterior end), sharp and high on the external surface, becoming 

 somewhat weaker inside ; they are closely and obliquely set, 

 separated by flat intervals of a moderate width. Only near the 

 anterior end of the shell, the ribs become dissimilar, some of 

 them being higher and broader than others, which proves the 

 growth at these points had been frequently checked. With the 

 exception of the anterior portion, the surface sculpture of this 

 species is so much like that of If. Otsuhai as to suggest the 

 existence of a relationship between the two species. In the 

 .spirally coiled, posterior portion of this shell, the siphuncle is 



