i8o Forest Marble. 



genera of shells. Corals occur in the Great Oolite, 

 including more than twenty species, chiefly belonging to 

 the genera Styling Isastrea, Thamnastrea, &c., and 

 Brachiopoda of the usual genera Rhynchonella (Rh. 

 concinna, &c.), and Terebratula(T. digona, T. obovata, 

 &c.), besides great numbers of Lamellibranchiata, the 

 most numerous of which belong to the genera Ostrea 

 (0. Sowerbii, &c.), Pecten (P. vagans, &c.), Ger- 

 villia (6r. monotis, &c.), Lima (L. cardiiformis, &c.), 

 Mytilus (M. imbricatus, &c.), Trigonia (impressa, 

 &c.), Cardium, Astarte, Ceromya concentrica, &c. 

 Pholadomya socialis, &c., Cyprina, Pecten, Lima, 

 and many others. Near Minchin-Hampton it is rich 

 in Gasteropoda, among the most common of which 

 are many of the genera Patella, Pleurotomaria, 

 Trochotoma, Purpuroidea (P. Morrisii), Natica, 

 Chemnitzia, Nerinea, Alaria, Ceritella, Cylindrites, 

 Turbo, and many others. Ammonites and Belemnites 

 are rare at Minchin-Hampton, but further south 

 Gasteropoda decline, and Cephalopoda are more nu- 

 merous. Echinodermata of the genera Acrosalenia, 

 Clypeus, Echinobrissus, and others are not uncommon, 

 and Pentacrinite joints occur rarely. Fishes' teeth, 

 Hybodus, Pycnodus, and Strophodus, and scales of 

 Lepidosteus are sometimes found, and reptiles of the 

 genera Teleosaurus and Megalosaurus, together with 

 the gigantic Ceteosaurus (or whale-lizard), probably 

 about 50 feet in length, and most likely amphibious. 



The Forest Marble forms the topmost beds of the 

 strata that usually are called Great Oolite. They are 

 formed of shelly limestone, with much false bedding, 

 very similar in structure to the Stonesfield Slate, and as 

 a marble the rock has sometimes been used for orna- 

 mental purposes. Its beds are full of Oysters, stems of 



