Heviews — Japanese Cejj/ialojjoda. 37 



extraordinary crumpling of the Devonians of the northern area, 

 and the flattening of their fossil beds, such as they were, into mere 

 films, are best explained on the presumption of a pressure of unusual 

 intensity, such as might result from a squeeze between two rock 

 masses of independent origin, viz., Dartmoor on the north and the 

 Metamorphic schists on the south. It cannot be denied that this 

 interpretation accords best with the stratigraphy of the region and 

 the general structure of the Damnonian peninsula ; possibly also, 

 in the main, with the petrology of the rocks of both the northern 

 and southern areas. 



11. — Cretaceous Cephalopoda from the Hokkaido. Part II : 



TuRRiLiTES, Helicooesas, Heteroceras, Nipponites, Olco- 



STEPHANUS, BeS3I0CERAS, HaUERICERAS, AND AN UNDETERMINED 



Genus. By Hisakatsu Yabe, University Hall, Imperial Uni- 

 versity of Tokyo. Journal of the College of Science, Imperial 

 University, Tokyo, Japan, vol. xx, art. 2, pp. 45 ; 6 plates. 1904 

 (published Oct. 15, 1904). 

 rpHE first part of this work (noticed in the Geological Magazine, 

 JL September, 1903) contained a description of those Ammonites 

 •which are included in the genus Lytoceras, s.str., and the genera, 

 or subgenera, JPseudophyllites, Gaudryceras, and Tetragonites. 



In this second part the following genera are described : (1) Turri- 

 lites, Helicoceras, Heteroceras, and Nip'ponites ; (2) Olcostephanus ; 

 (3) Desmoceras and Hnuericeras. " The order in which the different 

 groups are here treated is not due," says the author, " to the presence 

 of any mutual relations existing among them, but merely for the 

 sake of convenience and of avoiding too long a delay in the pub- 

 lication of the paper." 



Dr. Yabe has endeavoured to make his work on these Cretaceous 

 Ammonites from the Hokkaidd as complete as possible ; he has 

 studied not only their morphology, but the development of several 

 of their predominating types, "for," says he, "it has now become 

 clear that a mere morphological study of adult specimens is not 

 sufficient for the establishment of their real affinities, and that by 

 the study of their development only can such knowledge [be] 

 attained." 



Everyone who is acquainted with the Cretaceous Cephalopoda will 

 agree with Dr. Yabe that in their study " one of the most difficult 

 tasks is to define the exact limits of the different genera established 

 on the turreted forms of Ammonites." D'Orbigny included these 

 foi'ms under one of the three genera Turrilites, Helicoceras, and 

 Heteroceras, recognising in the first-named genus two distinct 

 groups, T. rotimdaii and T. angulati. Subsequently Sharpe and 

 Stoliczka referred the first of these groups to the genus Helicoceras, 

 reserving the name Turrilites for the group T. angulati. After 

 giving the various classifications that have been suggested for these 

 turreted forms, concluding with that proposed by Professor Hyatt 

 in 1900 in Eastman's translation of Zittel's Text Book of Palseon- 

 tology, the author says : — " Hyatt's classification by creation of 



