27 
(3) Cornbrash, Yorkshire; “ Macrocephalites ” typicus Blake, and other 
Macrocephalitid species. 
(2) Upper Cornbrash, Peterborough, a dark matrix as if in contact with 
an overlying clay deposit Dolikephalites dolius, Type Amm., ccclxxii. 
(1) Upper Cornbrash, Peterborough, a yellowish marly matrix, not in 
contact with an overlying clay and, therefore, presumably older than 
No. 2, Kamptokephalites Jcamptus , Type Amm., cecxnvu. A species 
of the same genus with a similar matrix among a series of Cornbrash 
fossils from near Cirencester, Gloucestershire. 
Species of Macrocephalitidae, therefore, according to these 
researches, which are by no means complete, extend into three forma- 
tions — from Upper Cornbrash, through Kellaways Clay into Kella- 
ways Rock. They mark some six different hemerse, possibly more; 
for there is reason to suppose that the rocks in which they are found 
are deposits of some nine or ten hemerse — nine or ten chronological 
units. In time it will be recognized that the Maerocephalitid-bearing 
strata of the world do not mark one synchronous date and, as the 
species become better known, it should be possible to separate them 
into the distinct dates for which the English species give evidence. 
Such dates may be tabulated as under: 
DATES OF MACROCEPHALITID-BEARING ROCKS 
Age 
(6) Proplarmlitan , . 
(5) 
(4a) Macroeephalitan. 
(4) 
(3) 
( 2 ) 
d) 
Hemera 
Galilaeiceras 
Catacephalites 
PI eurocephalites 
Macrocephaliceras 
typicus 
dolius 
kamptus 
Between (6) and (5) another hemera may have to be named and 
between (5) and (4a) three more hemerse have been named after species of 
Proplanulites (Type Amm., in, 1921, p. 40). 
77865 — 3 
