THE LIAS MARLSTONE OF LEICESTERSHIRE. 
155 
APPENDIX II. 
Xotes on the Palccontoloyy of the Marlstone of Leicestershire. 
With the exception of PJujnchoneUa tetraedra and Terehratula 
punctata, which are found everywhere, and in enormous 
numbers in the “jacks,” the fossils of the Leicestershire 
Marlstone are neither very numerous nor greatly varied. In 
comparison with the Marlstone of Oxfordshire the fauna is 
extremely limited. Mr. Beesley, of Banbury, gives a list of 
upwards of 250 species from the zone of A. spinatus in that 
county ; whereas for Leicestershire I am not able to mention 
more than a quarter of that number. Of these A. spinatus 
is rare, and except at Tilton, where we also get A. communis, 
A. annul atm, A. Holandrei, A. Coecilia (?), A. acutus, and A. 
serpentinus, no other ammonite is to be found. The remark¬ 
able abundance of A. acutus in the top bed at Tilton has 
already been mentioned. Belenmites occur everywhere in the 
Rock-bed, the prevailing forms being B. elonrjatus and B. 
paxillosus. The only other common fossils are Pecten aiquivalvis, 
P. lunularis, and Lima pectinoides. Some very interesting 
little Gasteropoda are to be found in the railway cutting south 
of Tilton Station, and also in a quarry on the east side of 
Pickwell, a village about three miles to the north-east. Both 
Rhynchonella tetraedra and Terehratula punctata show varietal 
forms : they also show great variations in the stage of growth 
of the shells, and the latter occasional monstrosities. 
The general character of the Marlstone Rock, its coarse 
arenaceous nature and oolitic texture, the occurrence of 
beds largely composed of shell fragments, the presence of 
current-bedding, and the occurrence of drift wood indicate 
that it was originally a shallow water, and probably a 
shore (if not an estuarine) deposit. The local development 
of this rock is, I believe, to be explained by original 
limitation of deposition and not by subsequent denudation. 
I have already mentioned that, on lithological grounds, 
the Marlstone Rock can be divided into two very distinct 
portions—an upper calcareo-ferruginous and fossiliferous 
division and a lower arenaceous and much less fossiliferous 
division. The Rock-bed cannot be further sub-divided into 
zones either on palaeontological grounds or by lithological 
characters. As a rule the “jacks,” of which there maybe 
one, two, or more, occur in the lower half of the upper or 
ferruginous series, but they are sometimes met with in the 
lower series. The “jacks ” rapidly pass into ordinary compact 
marlstone, and cannot be identified in the different exposures. 
