Except for the convenience of dividing so large a mass of strata, it would not be necessary to divide these from the Bembridge beds, as no break in the character of the life of the period occurs at the junction. The basement bed of the Hamstead strata is known as the Black Band, 2 feet of clay, coloured black with vegetable matter, with _Paludina lenta_ very numerous, _Melanopsis carinata_, _Limnaea_, _Planorbis_, a small _Cyclas_ (_C. Bristovii_), seed vessels, and lumps of lignite. It rests on dark green marls with _Paludina lenta_ and _Melanopsis_, and full of roots. This evidently marks an old land surface. About 65 feet higher is the White Band,--a white and green clay full of shells, mostly broken. There are bands of tabular ironstone containing _Paludina lenta_. Clay ironstone was formerly collected on the shore between Yarmouth and Hamstead and sent to Swansea to be smelted. The strata consist largely of mottled green and red clays, probably deposited in brackish lagoons. These yield few fossils except remains of turtle and crocodile and drifted plants. The blue clays are much more fossiliferous. Among other plants are leaves of palm and water-lily. The strata gradually become more marine upwards. The marine beds were called by Forbes the Corbula beds, from two small shells, _C. pisum_ and _C. vectensis_, of which some of the clays are full. Remains of early mammalia are found in the Hamstead beds, the most frequent being a hog-like animal, of supposed aquatic habits, Hyopotamus, of which there are more than one species.