1897- NOTES AND COMMENTS. 13 



has before now been hazarded that if they occurred at this horizon 

 at all, they would be found at the place where Mr. Abbott has 

 actually discovered them. 



Giant Ammonites. 



We understand that the British Museum (Natural History) has 

 acquired a magnificent specimen of the ammonite Haplocevas leptophyllus, 

 Sharpe, from the Upper Chalk of Rottingdean. It was one of 

 seven that were to be seen this summer between Brighton and 

 Newhaven, the largest of which reached the gigantic size of 5ft. 6in. 

 across, without the body chamber, but was almost destroyed when 

 discovered, and could not be moved. The specimen now at the 

 Museum is in a perfect condition, is 44 inches across, and shows a few 

 inches only of the body chamber. We believe that Mr. Crick will 

 contribute a note on its features and peculiarities to the Geological 

 Magazine, a note we shall await with considerable interest. 



Had the Belemnite an Aptychus ? 



Our recent remarks on the relations between stratigraphers and 

 palaeontologists find an appropriate illustration in a paper contributed 

 by Dr. H. P. Blackmore, of Salisbury, to the Geological Magazine for 

 December. There are found in the Chalk, as in earlier Mesozoic 

 strata, many of those peculiar bodies known as aptychi, and now 

 generally accepted as being the opercula of ammonites, corresponding 

 to the hood of the recent Nautilus (see Natural Science, vol. viii,, 

 p. 84, Feb., 1896). There is no question as to the correctness of this 

 view in the majority of cases ; but Dr. Blackmore, carefully collecting 

 zone by zone in his own neighbourhood, established the facts " that 

 Aptychus leptophyllus and Belemnitella lanceolata always occurred together 

 and that Aptychus Portlockii and Belemnitella quadrata were similarly 

 associated," and " that Aptychus rugosus was associated with B. 

 ■mucronata " ; further, no ammonite or nautilus is known in the zone of 

 B. lanceolata at this locality, but Haplocevas leptophyllus^ which occurs 

 at a lower zone, is associated with a coarsely tuberculate aptychus of 

 very different appearance. From these facts Dr. Blackmore infers 

 that the three aptychi mentioned above belong to no ammonite, but 

 to the belemnites with which they are respectively associated. 



As to the value and suggestiveness of these facts, there is no 

 question. Even if we doubt the main conclusion of Dr. Blackmore, 

 we receive from him a new guide for the determination of these 

 zones in all parts of the country ; and such facts can only be obtained 

 by the local collector and stratigrapher, whom we are doing what we 

 can to encourage and assist. But when we turn to the zoological 

 inferences of Dr. Blackmore, we find the existence and intervention 

 of the specialist fully justified. 



