434 
LOWER OOLITIC ROCKS OF ENGLAND : 
The following are the more abundant and characteristic species 
of the Cornbrash : 
Ammonites discus (Fig. 
119). 
macrocephalus (Fig. 
118). 
Nautilus. 
Avicula echinata (Fig. 
124). 
Cardium Buckmani. 
eognatum. 
Ceromya concentrica. 
Gervillia aviculoides. 
Goniomya v. scripta. 
Gresslya peregrina (Fig. 
121). 
Homomya gibbosa. 
Vezelayi. 
Isocardia minima. 
Lima duplicata. 
gibbosa. 
Modiola imbricata. 
- Lonsdalei. 
Myaeites calceiformia. 
decurtatus. 
securiformis 
(Fig. 120). 
Ostrea flabelloides. 
Pectcn deroissus. 
lens (Fig. 123). 
vagans (Fig. 122). 
Pholadomya deltoidea. 
lyrata. 
Trigonia elongata. 
Rhynchonella concinna 
(Fig. 77). 
Tcrebratula intermedia 
(Fig. 126). 
Waldheimia lagenalis 
(Fig. 127). 
obovata (Fig. 125). 
Serpula tricarinata. 
Acrosalenia hemicidaroides 
(Fig. 79). 
Echinobrissus clunicularia 
(Fig. 128). 
Holectypus depressus. 
Pygnrus Michelini. 
Anabacia complanata. 
As the Cornbrash exhibits so little variation in character, and 
if we except the Cornbrash Clays or " Avicula Shales " of Lin- 
colnshire and Yorkshire, it admits of no subdivisions, and it will 
be unnecessary to give many detailed sections of the strata. 
With regard to the fossils it may be stated that Terebratula 
intermedia occurs most abundantly in the lower beds, and 
Waldheimia obovata and W. lagenalis in the upper beds. These 
species, as well as W. ornithocephala and W. digona are, as Prof. 
Buckman remarked, very intimately connected.* 
The Cornbrash belongs to the zone of Ammonites macrocephalus. 
Oppel placed it, together with the Forest Marble, in the zone o 
Waldheimia ( Tcrebratula) lagenalis, but an Ammonite is a better 
zonal index. The z me of A. macrocephalus may be said to 
extend upwards into the Lower Oxfordian strata, and on the 
continent the Cornbrash and Kellaways Beds are sometimes 
grouped together under the general term Callovian. 
Paleeoutologically the Cornbrash in this country is regarded as 
the uppermost stage of the Great Oolite Series, and the beds are 
connected by the occurrence of euch common forms as Pecten 
* Ann. Nat. Hist., ser. 2., vol. xii. p. 326 ; Quart. Journ. Geol. Soc., vol. xiv. p. 122 ; 
Bee also Davidson, Appendix t<* Brit. Ool. Brachiopoda, p. 16. 
