Vol. 69.] THE ' KELL0WAY ROCK ' OP SCARBOROEGH. 167 



look like enough to be coufnsed (are homoeomorpkous) until they 

 are analysed ontogenetically, which is not always done. 



Such a heterochronous case, partly concerned with species dealt 

 with in the present paper, is not of the most striking kind, but it 

 deserves mention ; it is the case of the young costate Peltocems, 

 like enough to Dactylioceras of the communis type to cause the 

 former to be sometimes labelled as the latter and relegated to the 

 Lias, Now the former is anagenetic (renewed anagenetic, perhaps), 

 it is in the pre-tuberculate costate stage ; the latter is catagenetic, 

 it is in the post-tuberculate costate stage. 



By attention to the various phases of homceomorphy the apparent 

 tangle of ammonite species and the apparent anomalies of strati- 

 graphical records are found to come into definite order. Then it is 

 seen that the many names for genera and species are insufficient to 

 express the facts, and that more names will give a clearer picture 

 of the lines of evolution — that they are a real help to the memory, 

 .and not a hindrance. 



Discessiost. 



Mr. J. W. Stather remarked that the beds from which the old 

 ■collections were obtained are now inaccessible, being covered by 

 buildings at Scarborough and by landslips at Gristhorpe. These 

 fossiliferous beds occur in the uppermost part of the Kellaways 

 Rock, the remainder of the formation being practically unfossil- 

 iferous. He mentioned that the best opportunity for obtaining 

 Kellaways fossils in Yorkshire, during recent years, was in the 

 cutting on the Hull ife Barnsley Railway at South Cave, and he 

 hoped that the Author would examine the collections made by 

 the local geologists from that locality. 



Mr. L. F. Spath congratulated the Author on his most in- 

 teresting paper and the Society on receiving that valuable palseon- 

 tological contribution. When he thought of the state of hopeless 

 confusion in which Hyatt had left the classification of these 

 Callovian (as, indeed, of all other) ammonites, putting such closely 

 allied genera as, for example, Sigaloceras and Kepjilerites or 

 Erymnoceras and ReinecJceia, not only into different families, but 

 different super-families, and when he remembered the misdoings 

 of the French school, who at the present day included in the 

 Oxfordian genus Pctchyceras, so ably traced by the Author that 

 evening, even certain Portlandian holcostephanoids, he felt that 

 all palaeontologists must look forward to a study of the details of 

 this paper with the greatest interest. 



A point to which he desired to draw attention was the use of the 

 terms Callovian and Oxfordian. There was hardly a strati- 

 graphical term which was employed less definitely and less satis- 

 factorily at the present day than those terms Callovian and 

 Oxfordian, not only on the Continent, but also in this country. 

 In one great London museum, for example, even Kimmeridge-Clay 

 ammonites were labelled ' Oxfordian.' In the speaker's opinion 



Q. J. G. S. No. 274. w 



