A. J. Jukes-Broicne — Marsupites m Flints at Haldon. 449 



III. — The occurkence of Marsupites in Flints on the Haldon 



Hills. 

 By A. J. Jukes-Browne, B.A., F.G.S. 



WHILE examining recently a collection of specimens from the 

 flint-gravel of the Haldon Hills in the Museum of the Torquay 

 Natural History Society, I discovered among them four containing 

 casts of plates of Marsupites testudinarius. Moreover, in reply to 

 enquiries, Professor Clayden, of Exeter, informs me that the Albert 

 Memorial Museum there possesses five such plates, and that one was 

 found by Mr. F. J. Collins, of Exeter, about three years ago, so that 

 the fossil appears to be not uncommon in the Haldon flints, and 

 consequently it seems worth while putting the fact of its occurrence 

 on record, with some of the inferences that may be drawn from it. 



The casts are in pale grey flint, and it is somewhat remarkable 

 that they show a strongly marked arrangement of ridges corre- 

 sponding with those on the more ornate varieties of M. testudinarius. 

 As the inner surface of all plates of Marsupites is smooth, I conclude 

 that the plates embedded in flint were partially silicified, but even 

 then it is not easy to understand the persistence of the ornament, 

 unless this is structural and not merely an external ribbing. 



The coarse gravel which caps the Haldon Hills is now believed 

 to be of Eocene age, and Mr. C. Eeid has shown that the travel of 

 the stones composing these Bagshot gravels has been from west to 

 east. The flints, therefore, may be accepted as having been derived 

 from masses of Chalk, which then existed at a higher level than the 

 plateau which now forms the summit of Great Haldon, 



The existence of Marsupites in the Haldon flints is interesting, 

 because it testifies to the former extension of that zone of the 

 Chalk which alone yields this peculiar genus of Crinoidea. Dr. A. W. 

 Eowe has shown that the zone of Marsupites in the South of 

 England always consists of two bands or sub-zones, the lower 

 characterized by TJintacrinus and the upper by Marsupites, and 

 further, that plates of the latter genus very rarely occur in the lower 

 band, being almost restricted to the upper band. 



No Chalk now exists on Haldon, and the nearest outlier of Upper 

 Chalk is at Beer Head, a distance of about 18 miles, while the 

 nearest outcrop of the zone of Marsupites is a little west of 

 Dorchester, about 48 miles from the Haldon Hills. The highest 

 zone now remaining in Devonshire is that of Micraster cortestudin- 

 arium (near Beer), but the fossils found in the overlying flint-gravel 

 testify to the former presence of the zone of M. coranguinum, and 

 it has always been tacitly assumed that the higher zones of the 

 Chalk were also formed over Devon and other western counties. 

 We have now positive evidence of the western extension of the zone 

 of Marsupites, but at present there is no actual evidence of still 

 higher zones. 



So far as I can ascertain, no remains of Belemnites have been 

 found in the Haldon flints. Professor Clayden has kindly made 

 enquiries for me at Exeter, and has searched through the collection 



DECADE IV. VOL. IX. — NO. X. 29 



