ci: PII A LU rO DA FROM TRE JIOKKAIDO. ö 



/Spirocenfs. Stoliczka" said tluit " tlic poyitioii uf the sipliuncle 

 iuid the symmetrical or iin symmetrical division of the sutures 

 ought to be regarded as a much better distinguishing character 

 than the kind of volutions," while Meek'"^ argued, "it seems not 

 justified to unite typical Ilelicoceras characterized by very slender, 

 widely separated volutions, forming so broad a curve as to give 

 origin to a verv wide umbilical cavity and Turrilites roiuiidatl, 

 generally provided with much rounded, contiguous whorls." 



ZriTEL,"' in his Handbuch, accepted four subgenera of Turri- 

 Utes, namely Turrilltei^ s. str., Liiidr/ia (? Hell cane i/kcs), Ile- 

 ieroceras, and Helicocei'as. 



Remarkably different from the views above alluded to, are 

 those held by Neumayr and Hyatt. Neumayr"^' believed that 

 Hdicoceraa together with Toxoceras, Anisoceras, Plychoceras and 

 others should be In'ought under the genus H(f)ii,ües (in the wide 

 sense), while he placed Heteroceras near to Crioceras, a genus which 

 according to him is tolerably distinct from Turriliies and Ilamiles, 



According to a later publication of Hyatt,^^ these secondary 

 forms have no afHnity with Lytoceras and its allies, and conse- 

 quently are brought by him under Acanthoceratida and Cos- 

 moceratida. The genera which are treated as Acanthoceratids are 

 Helicoceras, Heteroceras, and Lindgla, which form his family of 

 Hamitidfc. . Of those placed under Cosmoceratida, Bostrycoceras 

 Hyatt is treated under Nostoceratidse, Helicancylus under An- 

 cyloceratidœ, Turriliies and Osilingoceras Hyatt under Turrilitidse, 

 and Hyphantoceras Hyatt under Anisoceratidie. 



1) Stui-iczka : i.e. p. Js:). 



2) Mekk : I.e. p. 487. 



Ö) Zittel: Handhncli tier Palaeontologie, I, 2. p. 44Ô. 



4) Xeujiayr; Die Ammoniteii der Kreide n. Systematik; d. Arunioiiitiden, pp. 894, 938. 



5) Hyatt: Cephalopoda in Zittkl's Text P>ook of Palaeontology, translated by Eastman. 



