Hastings Sand and Weald Clay. 205 



which was rewarded by the discovery of about twenty 

 species of mammals, belonging to the genera Spalaco- 

 therium^ Amblotherium, Peralistis, Achyrodon, Pter- 

 ospalax, Peramus, Stylodon, Bolodon, Triconodon, 

 Triacanthodon, and Plagiaulax. They are altogether 

 marsupial, and probably this Mesozoic mammalian 

 life was f low, insignificant in size and power, adapted 

 for insect-food, for preying upon small lizards, or on 

 the smaller and weaker members of their own low 

 mammalian grade ' (Owen). This mammalian fauna, 

 as far as it goes, at once suggests comparison with 

 the existing fauna of Australia, and the flora of the 

 time has in part like analogies. 



Overlying the Purbeck Limestone, in the Isle of 

 Purbeck, there are thick accumulations of interstratified 

 sand and clay, which belong to the geological horizon of 

 the Hastings Sand and Weald Clay. They are well 

 seen on the coast cliffs of Swanage Bay, and as far as I 

 know have yielded no fossils excepting fragments of 

 fossilised wood (fig. 75, p. 347). 



In the Isle of Wight, strata of the same general age 

 lie on the south-west coast, between Cowleaze Chine and 

 the neighbourhood of Compton Bay. In these there 

 occur Cyrena and Cypris and fragments of lignite, and 

 similar strata with the same kind of fossil remains are 

 found at the northern end of Sandown Bay. 



But the largest area of these estuarine beds now 

 exposed at the surface in England, is that of the Weald 

 of Kent and Sussex, which, between the North and 

 South Downs and the Lower Greensand, extends from 

 the great shingle banks of Dungeness on the east, to the 

 neighbourhood of Petersfield on the west, embracing an 

 area of about 80 miles in length, by about 25 miles in 

 breadth where its width is greatest. For the strati- 



