148 PROCEEDINGS OE THE GEOLOGICAL SOCTETY. [Jan. 8, 



referred to the Wealden, the Purbeck, and the Ehsetic, has heen 

 already pointed out. The finely laminated variegated clays, the beds of 

 fibrous carbonate of hme("beef" and "bacon" of the Purbeck 

 quarrymen), the bone-bed and numerous scattered fish-remains, the 

 admixture of dwarfed marine with fresh- or brackish-water species, 

 the bands crowded with Cyprides, and the abundance of Estherice, 

 all appear to indicate the prevalence, as in the formations referred 

 to, of estuarine conditions ; but they afford us no criteria for deter- 

 mining the age of the beds. Strata of almost identical mineral 

 characters occur in Sutherland at the base of the Middle Oolites ; 

 but I do not find any such community of species between the two 

 sets of strata as would justify their identification. The following 

 is the list of the species which have been obtained from the Linksfield 

 beds. 



List of Fossils from the LinJcsJield Shales. 



Femur of a species of Trionyx (deter- Modiola Hillana, Sow. 



mined by Professor Owen). , sp. 



Vertebrae of Plesiosaurus, sp. Astarte, sp. 

 Scales of Semiotus punctatus, A. So- Unio, sp. 



bertson, M.S. Cyrena. 



Lepidotus minor, Ag. Cyclas (several species). 



Pholidophorus, sp. Melanopsis, sp. 



Eugnatbus, sp. Paludina, sp. 



Teeth of Hybodus Lawsoni, Buff. Planorbis, sp. 



dubius, Ag. Candona ? globosa, Buff, sp. 



Sphenoncbus Martini, Ag. Estberia rninuta, Alberti, var. Brodie- 



Acrodus, sp. ana, Rupert Jones. 



Spines of Hybodus. Spine of Echinoderm. 



Ostrea, sp. Neuropteris and other ferns. 



Pteroperna, sp. Fragments of wood. 

 Mytilus, sp. 



Several of the species of marine mollusks which occur at Linksfield 

 appear to be undistinguishable from forms described by Professor 

 Hebert from the Bhaetic of Pfogonas, in Scania. But the evidently 

 dwarfed and abnormal condition of the fossils in both places is such 

 as to deter me from making any positive identification. 



The species of fishes described by Agassiz appear to be nearly all 

 peculiar to this locality ; but the general association of the genera, 

 though consistent either with the hypothesis of the Liassic or of the 

 Oolitic age of the beds, seems to be rather in favour of the former. 

 The marine mollusca are all evidently dwarfed, and the determi- 

 nation of their species thus rendered difficult and doubtful ; Mr. C. 

 Moore, however, has identified Modiola Hillana, Sow., a Lower Lias 

 form. The species of Cypris affords us no assistance ; but the Es- 

 theria, though belonging to a species having a very extended range, 

 is referred by Professor llupert Jones to a variety which has hitherto 

 been obtained only from the Bhsetic ; yet it is at the same time 

 shown to present some differences from the specimens undoubtedly of 

 that age. It will thus be seen that the palaeontological evidence 

 concerning the age of the Linksfield beds is far from being strong or 

 conclusive ; but the balance of it is certainty in favour of our con- 

 sidering the strata of Rbsetic or Lower -Lias age. 



