CEPHALOPODA FPvOM THE HOKKAIDO, 39 



]*>!•< 'adtli of tlio last wlioi-1 3..'] em. 37. 



Width of uiubilicLis 2.2 „ 2ö. 



Shell cliscoidal, compressed; when yoinig, whorls nearly roun<l, 

 with wide umbiliens ; when about 5 cm. in diameter, the whoid 

 enlarges rapidly in height, and is flattened on the sides. Involution 

 about one half or slightly less. The surface of the shell is covered 

 with very fine thread-like strijc which are somewhat flexuous. 

 The wliorl has neither periodic ribs nor furi'ows. There are 

 three bipartite saddles and lobes, all of which are finely toothed. 

 The three auxiliary saddles hang obliquely on the umbilical wall. 



This Ammonite shows a great resemblance to G. Yohoyamai, 

 from which it is distinguished l)v its compressed, comparatively 

 higher whorls and wider umbilicus. It also approaches G. 

 limatum, and appears to have a character intermediate l)etween 

 this species and G. Yokoyamai. 



Localities : — The Ikushuml)ets, Prov. Ishikari ; the IMakka- 

 ushipe, a tributary of the Popet, Prov. Iburi ; one from each 

 locality. The figure is that of the smaller specimen from the 

 Makka-ushipe. 



Horizon : — Upper Annnonite-beds. 



The two species — G. Yohoyamai and G. Yamashitai, have 

 been described from young individuals, as in the case of G. 

 politissimum from South India. Although their full grown speci- 

 mens are not yet known to the writer, still when judged from 

 their general shape, surface ornamentation and suture line, which 

 are all very peculiar, it is quite certain that they form a special 

 subgroup with G. Hmrdum as the type. 



