CEPHALOPODA FROM THE HOKKAIDO. oO 



1) A specimen from tlie Ikiisliumbets. (PI. IV., figs. 3 a, Ij). 



2) A specimen from the Yübarigawa. (PL IV., fig. 2). 

 Shell discoidal, somewhat compressed, composed of numerous 



^vho^]s ; whorls oblong, becoming gradually higher as the shell 

 grows, the broadest part lying near the umbilical edge. Umljili- 

 cus wide, shallow, exposing nearly three-fifths of the inner volu- 

 tions ; Umbilical wall perpendicular, suri'ounded by a rounded 

 edge. The suture of the shell except on the last volution is 

 smooth, being provided only with very fine stria? of growth. The 

 striic begin at the umbilical suture, bend forward at its edge and 

 extend into the lateral side of the whorl with a slight flexure, 

 passing straight over the ventral side. When the shell becomes 

 larger than about 8-9 cm. in diameter, the thick transverse 

 ril)s gradually begin to appear, encircling the whorl parallel to 

 the striœ and rapidly becoming broader and more elevated toward 

 the periphery. These ribs are broad, measuring 0.6 cm. in 

 average breadth with interspaces of about 0.4-0.8 cm. in breadth 

 on the siphonal line. However they become broader and more closelv 

 set together toward the mouth. Suture line very complicated ; the 

 external saddles as well as two lateral ones and the first auxiliary 

 are bipartite, while the remaining three auxiliaries are simple. 

 The lobes are narrow, the two lateral ones being bipartite. The 

 auxiliary saddles and lobes hang obliquely on the umbilical wall. 

 The septal lobe has been seen in a well preserved specimen. 



There is only one ally of the present form, and that is 

 Gaudryceras politisslmum Kossmat sj-».^^ from the upper Trichino- 

 poly group of Varagur, South India. This Indian species resem- 

 bles in many respects the Japanese. It is known (jnly by a 

 specimen at the middle stage of growth, which is distinguished 



1) KossiMAt: I. c. p. 32 [Via), PI. I. (XVj, tigs. 7 ;i, b, c. 



