8 THE GEOLOGIST. 



Professor Pictet has lately recognised among the fossils picked up 

 at St. Croix, in the Metabief Limonite, a well-preserved spioe of the 

 Asteracanfhus granulosus, Eger., a fish found by Mantell in the middle 

 division of the Tilgate beds. It is interesting to add that Campiche, 

 Pictet, and some other Jurassian geologists, have found in the same 

 Metabief Limonite numerous vertebrse, teeth, and scales of Plesiosaurus, 

 Crocodiles, and fishes, indicating that a rich fauna of vertebrated 

 animals existed there during the deposits of the Metabief beds (see 

 Description des fossiles du Terrain cretace de Sainte Croix, par Pictet 

 et Campiche. Geneve, 1858). If we remark that the middle division 

 of the Tilgate beds is precisely where Dr. Mantell found such 

 numerous remains of Plesiosauri, Crocodiles, Iguanodons, fishes, &c. ; 

 it is not improbable that we may synchronize the Lower Neocomian 

 with the Lower part of the Hastings Sands, from the Middle division 

 of the Tilgate beds downwards, with some degree of truth. I have 

 indicated this supposed synchronism by dotted lines. (See PI. L Ahst7xict 

 sections, &c.) 



We have as yet no palseontological evidence that will permit us to 

 identify the Middle and Upper Neocomian with the upper part of the 

 •Hastings Sands and the Weald Clay ; but, if the preceding synchronisms 

 be exact, we may accept this also on stratigraphical grounds. 



At all events, it appears from the preceding remarks, — 1st, that 

 the Neocomian is not the equivalent of the Lower Greensand ; 

 2d, that the Purbeck beds are coeval with the marine deposits called, 

 in the Jura, Salins Limestone ; 3d, that there is gi-eat reason to 

 suppose that the Neocomian of the Jura is the marine equivalent of 

 the Wealden of Kent, Surrey, and Sussex ; and that the gTcat gap 

 existing in Great Britain in the marine deposits between the strata of 

 Portland and those of the Lower Greensand will be filled up by the 

 Neocomian and the Salins Limestone of the Jura Mountains. 



