810 
THE CRETACEOUS ROCKS OF HRITAtNA 
Gaudryina are represented by Gaudryina pupoides and G. dispansa, 
the former not very common ; the latter with Lituola placentula 
were only found at Speeton. Tritaxias are absent. All the 
Foraminifera are of small size. 
Turning now to the residues of nine specimens of this zone 
from Dorset, Kent, and Herts, we find the families of Miliolidse, 
Astrorhizidse, and Lituolidse represented by five genera and only 
six species, and all of them are comparatively rare. The genus 
Textularia is represented by eight species, some very common; 
Tritaxia by two species, generally present; Gaudryina by three 
species, Gaudryina pupoides being very common ; Bidimina by 
eight species, Bulimina Presli and B. brevis being abundant. With 
the exception of Haplopliragmium nonionoides and one or two 
doubtful specimens, none of this genus were noted in this zone 
in the southern counties. Most of the species were large, bold 
forms, and differed in this respect very markedly from those of 
the north. 
As in the zone of Am. varians, the families of the Lagenidae, Globi- 
gerinidse, and Rotaliidoe were very generally distributed through¬ 
out the softer chalk of this division, and were all found in 
specimens obtained from the southern, south-eastern, and south¬ 
western counties. 
Of the Lagenidse, Oristellaria was the most common, Cristellaria 
gaultina occurring generally, none of the others being of frequent 
occurrence. Globigerina cretacea occurred everywhere, the speci¬ 
mens large. Although Globigerince are among the most prominent 
forms recognisable in thin slices, their proportion to the mass 
of the rock is very small. Amongst the Rotaliidce, Anomalina 
ammonoides was generally abundant. 
Ostracoda.— Valves of Ostracods are not very common in this 
zone. The only ones isolated were Bairdea subdeltoidea (Muenst.), 
Cytheris ornamentissimum (Reuss), Cythere koninckiana (Bos¬ 
quet), and Cytherella Muensteri (Roemer), all of which occur in 
the zone below. 
Finest Material. 
The amorphous calcareous material which constitutes so 
large a proportion of the upper part of the Grey Chalk differs 
from that of the Chalk Marl in being in a finer state of 
division ; the larger part of it consists of minute calcitic particles 
which give no hint of their derivation. The larger definite calcitic 
crystals described on p. 291, are less common, and the fragments 
which can still be recognised as pieces of shell or portions of the 
tests of Foraminifera are less abundant than in the Chalk Marl. 
Minute Foraminifera, chiefly Globigerina and Textulai ia, are 
frequently very common in the finest part of the washings. 
Crystalloids are abundant, but we have not been able to 
identify a coccolith. Rhabdoliths may be frequently seen. Fine 
