162 MR. S. S. BTTCKMAN ON [June 1913, 



suppose that at times there was not free communication between 

 the districts north and those south of the Humber. 



It is now for the Yorkshire geologists, or those who have the 

 opportunity to work the Yorkshire cliffs, to ascertain how far the 

 facts in the field agree with this armchair stratigraphy. Here, at 

 any rate, are the suggested points for consideration ; and, if only 

 building operations or slips of Boulder Clay have not concealed the 

 important beds, observation of the zonal sequence should not be 

 difficult. Further facts will be welcome, whether they confirm or 

 contradict the present suggestions. The object is to call attention 

 to the knowledge required, and to put forward something which 

 may be a working hypothesis — something which may stimulate the 

 attainment of further knowledge. 



Examinations of old collections may be useful, but it must be 

 remembered that the labels of localities in collections are not to be 

 trusted. Yorkshire aud Wiltshire specimens have been mixed, and 

 specimens from the Scarborough Limestone (Bajocian) and Scar- 

 borough ' Kelloway Rock ' have been interchanged. But they can 

 all be separated by examination of matrices : the matrix is really 

 the most trustworthy label that a fossil possesses. 



III. Palzeontoiogical Remarks. 



Ammonites ordinarius Bean-Leckenby (Leckenby, p. S). I 

 have reason to think that this is not a 'Kelloway Rock' species, 

 but is from the Calcareous Grit, and has been wrongly placed 

 and perhaps wrongly localized. If so, it is a Cardioceras more or 

 less nearly identical with Am. goliathiis d'Orbigny (pi. cxcvi, 

 figs. 1 & 2 only), and it may be a synonym of Nautilus ammonoides 

 Young & Bird. 1 



Cadoceras greavingki Pompeckj. 2 This species is hardly a true 

 Cadoceras, but it belongs to a series which in form and appearance 

 is intermediate between Cadoceras and Quenstedtoceras. This species 

 and its allies occur in the Kellaways Rock of Kellaways, and have 

 been placed sometimes as Ammonites marice d'Orbigny. The 

 ' Russian variety ' which he figures by that name 3 belongs to the 

 grewinglei series, but the other examples are quite distinct (see 

 Q. marice, p. 164). 



Cadoceras, sp. nov. Some of Bean's examples of Am. longcevus 

 belong here as a much compressed ally of C. grewinglei. The form 

 is also near to Quenstedtoceras primigenium Parona & Bonarelli. 4 



Cadoceras sdbl^ve J. Sowerby sp. By this name is intended 

 the small form figured in the lower right-hand corner of Sowerby's 



i ' Geol. Surv. Yorks. Coast' 2nd ed. (1828) p. 271. 



2 ' Jura-Fossilien aus Alaska' Verhandl. K. Russ. Mineral. Gesellscb. ser. 2, 

 toI. xxxviii (1900) pi. vi, figs. 1-3. 



3 ' Terr, jurassiques : Cephalopodes ' 1842-49, pi. clxxix, figs. 7 & 8 only. 



4 ' Call. inf. Savoie ' Mem. Acad. Savoie, ser. 4, vol. Ti (1895) pi. ii, fig. 4. 



