368 R. M. Brydone — Zone of 0. pilula, S. English Chalk. 



occur as isolated curiosities. Interest is therefore concentrated on 

 A. granulatus and A. quadratus. 



All my specimens, not a large number, from the loiver part of the 

 subzone of JE. scutatus, var. depressus, are too imperfect to be identified ; 

 they may with all probability be assumed to be ^. granulatus, as 

 Dr. Rowe appears to have found at that level. Belemnites identifiable 

 as that species, and there is no evidence yet that A. quadratus ever 

 ranged so low. 



At a point 25 feet below the top of the subzone, i.e. in its upper 

 half, I found a specimen broken but complete except for slight fraying 

 of the edges of the alveolar cavity. Mr. Crick and Dr. Blackmore 

 both regard this specimen as intermediate between A. granulatus and 

 A. quadratus, Mr. Crick saying " The specimen, although possessing 

 affinities with A. quadratus, seems to me to be more closely related to 

 A. gramdatus" ; and Dr. Blackmore saying that it "is, I believe, 

 A. quadratus, although the general contour of the specimen is rather 

 like that of A. granulatus, but the depth and f orm of the phragraaconal 

 cavity is that of the former species ". That the special features of 

 the specimen are not accidental is shown by the fact that some 

 4 miles away I found about 6 feet higher in the subzone the upper half 

 of a Belemnite with the alveolar cavity in perfect preservation and 

 agreeing exactly with the specimen submitted to Mr. Crick and 

 Dr. Blackmore. If in South England there occurred a passage fi'om 

 A. granulatus to A. quadratus synchronous with that which seems to 

 be generally accepted as having taken place on the Continent and 

 likely to be established for Yorkshire by Mr. Stather, the horizon at 

 which that passage took place would appear to be pretty closely fixed 

 by these specimens. (The specimen of A. quadratus recorded by me 

 from this subzone in Hants ^ came, as far as I can judge, from 

 a slightly higher horizon in the subzone.) I have found no other 

 identifiable Belemnites in this subzone in Sussex. 



In the subzone of abundant 0. pilula in Sussex I have only found 

 two Belemnites. One of them was found in the upper belt of 

 0. pilula, but only the lower end is preserved. It is either 

 A. granulatus or A. quadratus. The other specimen was found in the 

 Cinctus belt; it had already been severely attacked at the upper end, 

 but one side of the alveolar sheath still remained intact, and neither 

 Mr. Crick nor Dr. Blackmore has any doubt as to its being 

 A. quadratus. This agrees closely with Hants, where the only 

 Belemnite known from this belt of the subzone is a fine specimen of 

 A. quadratus, and where I have recently obtained a fairly certain 

 specimen of that species from the lower belt of 0. pilula. 



In the zone of A. quadratus on the Sussex coast I have just 

 obtained a specimen of A. quadratus about 8 feet above the zone of 

 0. pilula, the first Belemnite I have yet seen in all the chalk of this 

 zone that is accessible. 



On the cognate subject of Ammonites, known to occur freely on 

 this coast, it is worth noting that I have seen a great many, all of 

 which were in the zone of 0. pilula, and all but one in the subzone 



^ The Stratigrai^hy of the Chalk of Hants, p. 11. 



