﻿Vol. 66.] JURASSIC STRATA OF SOUTH DORSET. 81 



accident, from a man who had been employed as a mason on the 

 line ; and, in a collection of Ammonites sent to me for determination 

 from Yale University, New Haven (Conn.), U.S.A., there was a fine 

 Hammatoceras without further localization than England : there is 

 no doubt that it came from Cole, on account of its condition and 

 matrix. These Hammatocerata mark the Yeovil Sands of Cole as 

 belonging to the dispansi hemera in date ; but I have never had 

 the opportunity of inspecting the deposit in this neighbourhood. 



To return to the moorei-Dumortieria beds. In North Somerset, at 

 Dundry, the Dumortieria Beds appear as a thick clay- deposit. In 

 the Cotteswolds, they and the moorei beds are found as a thin 

 deposit of ironshot marl or marly stone, in the middle of the so- 

 called ' Cephalopod Bed ' ; but they are not recorded in the Cotteswolds 

 north of Haresfield. There is some indication of the beds at Bredon 

 Hill, 1 but in the rest of the Lias outcrop they are not known until 

 they are met with as ' [the Yellow and] Grey Sands below the 

 Dogger ' of the Yorkshire Coast." 



The ' Grey Sands ? are also divided as the Lingula Bed, and the 

 Serpula Bed above it. 3 



Hudlestonia sinon (Mon. Amm. p. 227) is from the Grey Sands. 

 H. affinis (Hid. p. 229) was sent as from the ' Yellow and Grey 

 Sands'; but presumably it is from the Grey Sands: these species 

 indicate Dumortieria date. Dumortieria rnunieri (Mon. pi. xxxvii, 

 figs. 14 & 15), evidently from BleaAVyke (Yorkshire), ought to be from 

 the same beds. On this evidence the ' Grey, but not the Yellow, 

 Sands ' are of Dumortieria date ; but whether it is the Lingula Bed 

 or the Serpida Bed, or both, that are of this date is uncertain. 



The identification of Ammonites quoted from these beds cannot 

 be trusted, unfortunately. A specimen in the Museum of Practical 

 Geology (Jermyn Street), 4423, labelled ' Am. aalensis var. Moorei, 

 bottom bed,' cited by Mr. C. Fox Strangways 4 and by Mr. K. H. 

 Rastall 5 as from the Serpula Bed, is really an unidentifiable frag- 

 ment of a body-whorl 1 j inches long. It shows remains of a small 

 distinct carina, which makes its agreement with any aalensis form 

 (Fam. Hildoceratidas) or any moorei form (Fam. Polymorphidae) 

 almost impossible. It shows a Hildoceratid radial line, agreeing 

 with fig. 155, Monogr. Suppl. p. clxvii. which happens to be 

 Phlyseogrammoceras orbignyi, a species sent to me by Hudleston 

 from the striatidus beds (Mon. p. 188) but suggestive of disjxinsum 

 date. This, therefore, should not occur above the Lingula Bed 

 (Dumortieria) except by derivation ; the evidence of a fragment like 

 this, even if determined with some certainty, is not of any value. 



Since the above was written, Mr. L. Richardson has shown me 

 specimens of Ammonites collected by him 4 feet from the top of 

 the Lingula Bed : they are Hudlestonia sp. (affinis form) and 



1 Quart, Journ. Geol. Soc. vol. lix (1903) p. 447. 



2 ' Monogr. Inf. Ool. Amm.' (Palaeont, Soc.) p. 168. 



3 W. H. Hudleston, Proc. Geol. Assoc, vol. iii (1874) p. 296. 



4 ' Jurassic Kocks of Yorkshire ' vol. i, Mem. Geol. Surv. 1892, p. 153. 



5 Quart. Journ. Geol. Soc. vol. lxi (1905) p. 444. 



Q. J. G. S. No. 261. o 



