STONESFIELD SLATE. 
345 
beds shells of the genera Patella^ Nerita^ Rimula^ Cylindrites 
are common (see Figs. 334 to 337); while cephalopods are 
rare, and instead of ammonites and belemnites, numerous 
genera of carnivorous trachelipods appear. Out of 224 spe¬ 
cies of univalves obtained from the Minchinhampton beds, 
Mr. Lycett found no less than 50 to be carnivorous. They 
belong principally to the genera Buccinum^ Pleurotoma^ Bos- 
Fig. 332. 
Terebratula digona. 
Sow. Nat. size. 
Bradford Clay. 
Fig. 333. 
Purpuroidea nodulata. One- 
fourth natural size. Great 
Oolite, Minchinhampton. 
Fig. 334. 
Cylindrites acutus. Sow. 
Syn. Actceon acutus. 
Great Oolite, Minchin¬ 
hampton. 
tellariayMurex^Purpuroidea (Fig. 333), and Pusus, and exhibit 
a proportion of zoophagous species not very different from 
that which obtains in seas of the Recent period. These zo¬ 
ological results are curious and unexpected, since it was im¬ 
agined that we might look in vain for the carnivorous trache- 
lipods in rocks of such high antiquity as the Great Oolite, and 
ig. 335. Fig. 336. Fig. 33T. 
Patella rugosa, Sow. Nerita costulata^ Desh. Rimula {Emarginula) 
Great Oolite. . Great Oolite. clathrata^ Sow. Great 
Oolite. 
it was a received doctrine that they did not begin to appear 
in considerable numbers till the Eocene period, when those 
two great families of cephalopoda, the ammonites and belem¬ 
nites, and a great number of other representatives of the same 
class of chambered shells, had become extinct. 
Stonesfield Slate: Mammalia. —The slate of Stonesfield has 
been shown by Mr. Lonsdale to lie at the base of the Great 
Oolite.* It is a slightly oolitic shelly limestone, forming 
large lenticular masses imbedded in sand only 6 feet thick, 
* Proceedings Gteol. Soc., vol. i., p. 414. 
15* 
