Coral Rag. 185 



chiopoda and Lamellibranchiata, of genera and some 

 species common to all the Oolites, are common. The 

 Oxford Clay also contains many Belemnites, Ammo- 

 nites, and other shells, among which, Ammonites 

 Jason, Ostrea flabelloides, and Gryphcea dilatata 

 are characteristic of this formation. Trigonia costata, 

 an inferior Oolite species, passes upwards thus far. 

 The general assemblage of fossils in the Oxford Clay 

 and Kelloway Eock generically, and largely in species, 

 strongly resembles that of the Lower Oolite formations, 

 but the life is not so numerous. Fishes, Hybodus, 

 Lepidotus, and Pycnodus are found, and Eeptilia of 

 the genera Dakosaurus, Ichthyosaurus (I. dilatatus 

 swdthyreospondylus), Megalosaurus Bucklandi, Pleio- 

 saurus gamma and P. grandis, 4 species of Plesio- 

 saurus, P. Oxoniensis, &c., Rhamphorhynchus 

 Bucklandi, Steneosaurus, and Streptospondylus 

 Cuvieri. 



The plentiful assemblage of fossils in an accidental 

 stratum so thin as the Kelloway Eock, lying in the 

 Oxford Clay, speaks of physical conditions in the sea 

 favourable to the development of life, and the diminu- 

 tion of species in the thick beds of the Oxford Clay 

 seems to tell of the deepening of a sea in which much 

 muddy sediment was being deposited. 



The CORAL EAG is a rubbly limestone, trending, 

 with occasional interruptions, from Somersetshire to 

 Yorkshire, the details of which it is unnecessary to give. 

 It is associated in places with sandy strata known as 

 the Calcareous grits, and is often almost entirely com- 

 posed of broken shells and Echini, Gidaris Smithii, 

 Hemicidaris intermedia, Pyg aster umbrella, Py gurus 

 costatus,&c., and numerous corals (whence its name) of 

 the genera Isastrea, Thecosmilia, Protoseris, &c., 



