Symonds — British Fossil Mammals, 415 



relic do the intervening strata furnish. It is true that those strata 

 were in all probability deposited at a considerable distance from 

 land. Nevertheless we must feel assured that throughout all those 

 periods which elapsed, during which the whole of the Lias and 

 Inferior Oolite beds were deposited, Mammalia of some kind or other 

 must have lived upon the neighbouring shores, but of which not a 

 single fragment has yet been detected. The Stonesfield slate, which 

 lies at the base of the Great Oolite, appears to be either a shore- 

 deposit, or a shore-deposit broken up and redeposited in somewhat 

 deeper water. It contains marine shells, fossil wood, with the im- 

 pressions of ferns, cones, and other parts of land plants. The remains 

 of insects are sometimes beautifully preserved, and no less than ten 

 jaws of small quadrupeds belonging to three distinct genera have 

 been found in these rocks. All of these animals are believed to 

 have been Marsupials. 



There are few persons who are not acquainted with the '' Purbeck 

 marble," which is so much used for shafts and columns in many of 

 our old English cathedrals and churches. The Purbeck marble 

 belongs to the uppermost division of the Oolite rocks, and is a fresh- 

 water limestone, containing freshwater shells and fishes. In the 

 Purbeck series eight or nine genera and about fourteen or fifteen 

 species of plant-eating, insectivorous, and predacious Marsupials have 

 been found by Mr. Beckles and Mr. Brodie. Of one of these 

 Mammalia, the Plagiaulax, the late Dr. Falconer says that " it may 

 be regarded in the natural system as a marsupial form of rodent," 

 and '' may have had the volant habits of the flying Plalangers, and 

 flitted from tree to tree among the Oolite forests by means of para- 

 chute-folds of their skin." (Falconer's Palaeontological Memoirs, 

 vol. ii. p. 425.) These Purbeck Mammalia lived in the same Oolitic 

 period with the strange birds of Solenhofen, birds with tails like 

 lizards (the Archtsopteryx) , and also with the gigantic reptiles that 

 abounded in those days on the land and in the rivers and seas. Yet 

 another change occurred, and we have a long lapse of time, during 

 which all evidence of the existence of Mammals is again wanting. The 

 seas of the Chalk period rolled their waves for ages above the tombs of 

 the Purbeck Mammalia, and with the exception of some winged reptiles 

 [Pterodactyles) , and a few pieces of drift-wood, all the fossils of the 

 Chalk indicate the existence over a large portion of our northern 

 hemisphere of a wide open sea. During that long protracted epoch, 

 the Secondary epoch, the northern hemisphere appears to have been 

 occupied far more by sea than land, so that the Secondary rocks are, 

 with one or two exceptions, solely the remains of sea-beds widely 

 spread, and deposited in the course of long ages one above the other. 

 With the exception of the freshwater strata of the Wealden and 

 Purbeck beds, the great masses which constitute the Secondary rocks 

 are all of marine origin. No sooner, however, do we examine the 

 Lower Tertiaries, than we find evidences of the elevation of land 

 throughout an area over which, during the antecedent period, there 

 rolled the waves of a deep Cretaceous sea, and on this elevated land 

 we know there lived numerous strange and extinct quadrupeds. 



