G. E. Grimes — Radiolarians in Chalk, 345 



e. Purple -coloured quartzite boulder or pebble, 5|in. X 4.iin. X 3 m., a 

 flattened oval iu form, covered with depressions of a less decided type than 

 a or b. The surface of the depressions are white from a deposit of silica 

 therein. There is only one small adherent bit of gravel. The opposite side 

 to that shown in the photograph has no " pittings," but a good many small 

 adherent patches of sand about ^ inch in diameter, apparently indicating the 

 points of contact of small pebbles or gravel, now removed. There are 

 depressions on the edges. (Stile Cop.) 

 Fig. 2. — The boulders shown are the same as in Fig. 1, but arranged in a way to 



get the light from another direction to show up some of the features not 



properly developed in Fig. 1 . 



II. — Two Occurrences of Eadiolarians ik English Cretaceous 



Rocks. 



By George E. Grimes, B.Sc, A.R.S.M., A.E.C.S., F.G.S. 



THE opinion that fossil Radiolarians were entirely limited to 

 Tertiary strata prevailed until a comparatively late period. 

 Prof. Ernst Haeckel, in his monograph on the Radiolaria, published 

 in 1862, says " that the Radiolarians made their appearance for the 

 first time during the Tertiary period"; and Ehrenberg, as late as 

 1875,1 defined all the Polycystina-bearing rocks as Tertiary. 



For a long time the Cretaceous rocks yielded but few remains of 

 Radiolarians, and even as late as 1885 Dr. Riist remarked on the 

 poverty of Radiolarian remains in Cretaceous strata.^ Since that 

 date, however, chiefly owing to the patient and laborious researches 

 of Dr. Riist, a large number of species have been obtained from 

 various rocks on the Continent, principally from the Lower 

 Cretaceous.^ 



Prof, Sollas was the first to notice Radiolaria in the Cretaceous 

 rocks of this country, and in his paper " On Greensand Sponges and 

 Foraminifera"* he says : " Polycystina of various genera also occur; 

 forms resembling Ealiomma may be noticed of somewhat frequent 

 occurrence." Prof. Sollas promised a full description of these forms 

 later, but I believe it has not yet appeared.^ 



In 1888 Dr. Riist'' described two species — BicUjomitra anglica 

 (Riist) and Diclyospyns cldamijden (Riist)— from flints of Senonian 

 or Turonian age' from England; but the locality is not given. 



The object of this paper is to describe two fresh occurrences of 

 Radiolaria in our Cretaceous rocks. 



One is in the Fuller's Earth Rock Bed in the Lower Greensand, 

 between Redhill and Nutfield, Surrey. This bed lies directly on 



1 Fortsetzung der mikrogeologischen Studien : Abhandl. der k. Akad. der Wissen. 

 Berlin, 1875. 



2 Beitrage zur Kenntniss der fossilen Eadiolarien aus Gesteinen des Sura: 

 Palaeontographica, vol. xxxi. 



^ Beitrage zur Kenntniss der fossilen Eadiolarien aus Gesteinen der Kreide: 

 Palaeontographica, vol. xxxv. 

 * Geol. Mag., Vol. X, 1873. 



5 It shoidd also be mentioned that Dr. Wallich recorded the occurrence of several 

 genera of Eadiolaria in the interior of Chalk flints iu 1883 (Ann. and Mag. Nat. 

 Hist., July 1883, p. 52).— Edit. Geol. Mag. 



6 Beitrage zur Kenntniss der fossilen Eadiolarien aus Gesteinen der Kreide: 

 Palaeontographica, vol. xxxv. 



