362 R. M. Brydone — Zone of faster pilula. 



taken as the top of the zone. This band is accessible for a long 

 distance in a wave-beaten section at Friars Bay, for a short distance 

 in a favourable condition near Brighton (where the upper boundary 

 is hardly marly and is little more than a parting), and for some 

 distance, in parts of which it is in fair condition, in Meeching Quarry, 

 Newhaven. I have not yet found even a small specimen of a normal 

 Marsupites plate in this band ; but small and dwarf Crinoid brachials, 

 such as are otherwise only found in association with Uintacrinus or 

 Marsupites, range all through this band and are fairly abundant, while 

 occasionally very small Crinoid plates are found which may be 

 indistinguishable from plates of Marsupites except for their smallness 

 or may be practically oblong with about -§- in. of their length flat at each 

 end and the remainder arched. (I have once or twice found similar 

 plates in Hants in beds which probably occupied the same position, 

 just above the highest undoubted plates of Marsupites.) Terebratulitia 

 Rowei is also present throughout this band and in an abundance 

 which seems quite unusual to me. At the top of this band of chalk 

 T. Rowei and the dwarf plates disappear absolutely, and the brachials 

 disappear so nearly absolutely that I have only met with very few 

 above this band, all of which were in the lowest foot of the succeeding 

 bed. I have also from this band one pyramidate E. scutatus, which if 

 not typical of the var. elevatus is very much nearer to it than to the 

 var. tectiformis. On these grounds I have attributed this band to 

 the zone of Marsupites. Bourgueticrinus Form 5 has not yet been 

 found in this band nor in the upper beds in which undoubted plates 

 of Marsupites occur, and this confirms an impression I have derived 

 from the Hants sections that it disappears before the top of the zone 

 of Marsupites is reached. It is curious how consistently it seems to 

 anticipate T. Rowei, which is commonly treated as having the same 

 range. Thus Bourgueticrinus Form 5 is well established some way 

 below the Uintacrinus band ; T. Roioei appears to come in only 

 a very little way below the Uintacrinus band ; Bourgueticrinus 

 Form 5 disappears apparently in the course of the zone of Marsupites, 

 T. Rowei at its end. Bourgueticrinus Form 5 reappears in the middle 

 of the subzone of ^. scutatus, var. depressus, and does not seem to outlive 

 it ; T. Roioei does not reappear until the subzone of abundant 

 0. pilula, and persists almost, if not quite, all through it. 



It will be observed that the lithological features by which I have 

 divided up the subzone are exclusively marl bands. This does not 

 mean that I do not attach any value to lines of flint as permanent 

 features, for I hold that they are very often persistent enough to be 

 very serviceable. A conspicuous instance may he found in the bed 

 I have treated as the highest bed of the Marsupites zone ; this bed 

 between Brighton and Rottingdean contains a line of flints from 1 foot 

 to 18 inches down and another 3 feet lower ; its flints are distributed 

 in exactly the same way in Friars Bay, 5 miles away, and again a mile 

 further on in Meeching Quarry, Newhaven, and at Seaford Head. 



A good deal of scorn has been heaped upon the idea of lines of flint 

 being sufficiently persistent to be of use as indices to horizon, but it 

 will be found that many of the cases cited are really irrelevant, being 

 cases of the irapersistence of tabular veins. The presumption being 



