102 PEOF. MORETS — GEOLOGY OF THE LONDON BASIN 



represented. Amongst the Vcrtebrata we have each class repre- 

 sented — Fishes, Reptiles, Birds, and Mammals. Amongst the 

 most numerous are some very curious forms of fish. The fish of 

 the London Clay period indicate to us a great Natural History fact 

 — that whereas, of the fish in the Chalk period most of the forms 

 are now extinct, or belong to the shark and ray tribe, and there 

 Avere only a very few species related to the present most abundant 

 fish-life forms, in the London Clay there were not only sharks 

 and rays, as shown by their well-preserved teeth and palates, but 

 a great number of forms allied to those which constitute the larger 

 portion of the existing fish fauna, the Cycloid and Ctenoid, or 

 Teleostean fishes. This therefore shows that, in one group at 

 least of fishes, — the Teleostei, there has been a gradual increase 

 from the Chalk period to the present time ; and the phsenoga- 

 mous plants exhibit a similar increase. 



Besides the fish, there are numerous forms of reptile life — 

 the Crocodiles, and also the Ophidia (snakes), which here 

 appear for the first time ; for no traces of this order have been 

 noticed before. In the London Clay also is found another interest- 

 ing order — the Chelonia or group of turtles. No less than nine 

 different species of turtle occur, whereas at the present time in all 

 the seas of the globe there are only five known living species, and 

 they are widely distributed. These indicate warm conditions ; 

 and with them are found river turtles and tortoises. Many species 

 of Crustacea, Xanthopsis, Hoploparia, etc., some Echinodermata, 

 numerous Foraminifera, and Entomostraca, also occur. Of the more 

 remarkable Mollusca is the Nautilus, with eight or ten fossil species, 

 although there are only two living ones ; and there are also 

 numerous species of Volufa, Fusus, Cyprcca, Pleurotoma, which 

 afford another indication of comparatively tropical conilitions. 



But besides the crocodiles and turtles as e\idence of rivers and 

 shores, we find imbedded in the clay of Sheppey and other dis- 

 tricts remains of certain Mammalia of curious forms [Hyracothe- 

 rium, FUolophus) — not of existing genera, but related to existing 

 genera — which must have lived on the land of that period ; and 

 still more interesting, in the neighbourhood of Sheppey and else- 

 where are found abundant traces of vegetation of large growth and 

 of different characters : fruits and seeds, which by a careful 

 comparison of existing forms indicate the very singular fiora 

 which grew upon tlie high and low lands of the London Clay 

 period, and some curious forms of Coniforai which yielded the 

 Highgate resin or fossil amber, and of Proteacea!, a family 

 almost only represented at the present day in the arid forests of 

 Australia, 



Fruits related to the Acacia, Gourd, Melon, and Custard- 

 apple families are associated with a largo number of so-called 

 "fossil figs" {Xipadites), which bear a close resemblance to the 

 remaikal)U! gcTius -N^ipa, growing so abundantly in the ^Molucca 

 Islands and the region of the Ganges, and wliich fre(iueiitly come 

 down the river in such numbers as almost to stop the navigation. 



