Dr. J. W. Gregory — Fossils from tlie Lower Oreensand. 99 



Bather has kindly examined my specimens with care, and determined 

 them all to be T. Fiifoni. 



The above list, therefore, adds 15 species to the fauna: these are 

 of interest as they are forms with a more restricted distribution than 

 the 11 valid species in Mr. Topley's list. The following table shows 

 the affinities of the species : — 



Species confined to Neocomian 2 (both doubtful) 



,, ,, Aptian 8 



Gault 4 



,, ranging from Urgovian to Aptian 2 



,, ,, Neocomian to Aptian 1 



,, ,, ,, Gault 1 



,, ,, Aptian to Gault 3 



,, ,, Aptian to Upper Greensand .. 3 



This summary clearly shows that the affinities of this fauna are 

 with the Aptian or Gault ; for of the 24: species included, 18 occur 

 in the former, and 11 in the latter, while 15 are confined to the two 

 stages. Two species occur only in the Neocomian, but they are 

 based only on internal casts of univalves, and their evidence is of 

 little value. The affinity is closest with the Aptian, but the fact 

 that 11 species are present which occur in the Gault and that three 

 range into the Upper Greensand, point to the fauna being high up 

 in the Aptian stage. 



This is in full agreement with the stratigraphical evidence; for 

 the bed overlies the Kentish Ra^, and occurs below the Gault, though 

 the direct superposition of the latter is not shown in the section. 



IV. The Value of the Sandgate Fauna. 



The fauna having been thus determined as Upper Aptian, both 

 from palgeontological and stratigraphical evidence, there remains 

 only the question as to whether it is most allied to that of the 

 Sandgate or that of the Folkestone divisions of the Lower Greensand, 

 and whether there is adequate palajontological reason for the separa- 

 tion of these two beds. 



Eight of the species in the bed at Great Chart occur in the 

 Sandgate Beds in the district where that stage is most typically 

 shown. All of these, however, with the exception of Arciica 

 angnJata, occur also in the Folkestone Beds at Folkestone ; and in 

 this there is another species [Thetis IcBvigata), found at Great Chart, 

 but not yet recorded from the Sandgate Beds of Sandgate. Thus 

 palajontologically the Great Chart phosphatic bed is as closely allied to 

 the Folkestone as it is to the Sandgate Beds. It may be objected that, 

 as of these nine species six also occur in the Hythe Beds of Hythe, 

 Lympne and Maidstone, the palaeontological evidence is too indefinite 

 to be worth much. This, however, only proves that the Hythe, Sand- 

 gate, and Folkestone Beds represented a comparatively short period. 

 The species characteristic of the Hythe stage do not occur in either 

 of the latter at Folkestone or Great Chart. The Sandgate and 

 Folkestone Beds together contain a number of species which are 

 chai'acteristic of a higher horizon. Such are Waldheimia Wanklyni, 

 Terebratella Fittoni, Ehynchonella sulcata, Astarte allohrogensis, 



