26 ART. 2. — H. YABE I CRETACEOUS 



with exceedingly fine striœ and five periodic elevations. The 

 suture is similar to that of the normal form, the head of the 

 first auxiliary saddle touching the umbilical suture which is 

 followed by two or three small denticulations. 



This variety is distinguished by a very slow growth of whorls 

 and an umbilicus wider than the normal form. The writer 

 thought at first that this form was a distinct species, and probably 

 identical with G. Kayei Forbes sp. from the Senonian deposits of 

 S. India, ^^ Natal,-^ Chili'"'^ and Tunis,'*^ whose European ally is G. 

 planorhiforme Böhm sp.;^^ but the presence of many transitional 

 forms between this and the normal specimen of G. tenuiliratum 

 convinced him that it is impossible to treat them as different 

 species. 



The above mentioned characters being common to this variety 

 and G. Kayei, it is doubtful whether the greater part of the 

 forms described as G. Kayei are not a mere variety of G, 

 tenuiliratum. 



It is quite impossible to decide whether an Ammonite described 

 under the name of G. 'planorhiforme resembles Senonian or Ceno- 

 manian forms when we have only young specimens. The writer 

 is also in doubt whether the large individuals figured in PI. 

 XXXIV. fig. 4, 5. and PI. XXXV. fig. 7, by A. de Grossouvre 

 really belong to the adult stage of G. planorhiforme. 



An Ammonite from the Vancouver Cretaceous first described 



1) Stoliczka: 1. c. Kossmat: 1. c. 



2) Griesbach : 1. c. 



3) Steinmann: 1. c. 



4) L. Pekvinquière : 8ur nn faciès paiticularier de Sénoinen de Tunisie. 1898. (by 

 référât). 



5) J. Böhm: Palœontograpliica. Bd. XXXVIII. p. 49, PI. I. fig. 12— V. Uhliq : 

 Bemerkungen z. Gliederung karpath. Bildungen. Jahrb. d. k. k. geol. Reichsanstalt. Wien, 

 1894. P. 216, fig. I.-Geossodvre : 1. c. p. 231, PI. XXVII. fig. 2. 



