OF THE SWISS JURA AND ENGLAT^D. 



259 



The question arises how many of these subdivisions represent 

 the ' Terrain a chailles siliceux.' We have already seen that the 

 Oxfordian is on the horizon of the Lower Calcareous Grit, and some of 

 the fossils from the ' Terrain a chailles siliceux ' also connect it with 

 the Lower beds of the Corallian, as for example : — 



G-ervillia aviculoides, Sow. 

 Waldheimia bucculenta, Sow. 

 Rhynchonella Thurinanni, Br. 



Millericrinus echinatus, Schl. 

 Gryphaea dilatata, Sow. 

 Belernnites hastatus, Blainv. 



None of these occur above the Hambleton Oolite in England. 

 The siliceous beds in the Jura also contain : — 



Ammonites plicatilis, Soiv. 

 Chemnitzia heddingtonensis, Sow. 

 Ostrea duriuscula, Phil. 

 Lima pectinitbrmis, Schl. 

 Terebratula insignis, Schub. 

 Cidaris ilorigemma, Phil. 

 Hemicidaris intermedia, Flem. 



Phasianella striata, Sow. 

 Trigonia monilifera, Ag. 

 Mytilus pectinatus, Sow. 

 Glypticus hieroglyphicus, Ag. 

 Stomechinus gyratus, Ag. 

 Clypeus subulatus, Y. § B. 

 Montlivaltia dispar, Phil. 



All of these are characteristic of the Coralline Oolite and Coral Rag. 

 The sub-zone of Cidaris florigemma (Coral Rag) is marked in England 

 by the abundance of this Echinoid, and it is in fact almost limited 

 to this horizon *. In the Jura it makes its first appearance in the 

 ' Terrain a Chailles siliceux,' and extends up to the Pterocerian ; as 

 far as was seen by us, however, it occurs abundantly only in the 

 ' Terrain a Chailles siliceux.' Glypticus hieroglyphicus is also fairly 

 common in these beds in the Jura, although it is said to range 

 into the overlying ' Oolithe corallienne ' and ' Calcaire a Nerinees'; 

 in England it is confined to the Coral Rag. On palseontological 

 grounds therefore the ' Terrain a Chailles siliceux,' while probably 

 representing some portion of the lower divisions of the Corallian 

 (e. g. the Hambleton Oolite), must also be regarded as the equivalent 

 of the other subdivisions of the Corallian of England, up to and 

 including a part at least of the Coral Rag. 



It has already been shown that the Corallian of the southern dis- 

 trict in the Jura probably represents only the ' Terrain a Chailles 

 siliceux ' of the district further north. Jaccard {op. cit. p. 204) gives 

 a list of 55 species from these beds, 20 of which occur in the British 

 Corallian, and 12 belong exclusively to the Coral Rag and Coralline 

 Oolite. Here, again, the evidence is clearly in favour of the corre- 

 lation indicated above for the ' Terrain a Chailles siliceux/ 



The Oolithe corallienne has, as already shown, been recognized 

 only in the northern district of the Jura, and has yielded a fauna 

 consisting of 44 species, 10 of which occur in the Coral Rag and 

 Coralline Oolite of England. These 10 species include — 



Ammonites plicatilis, Soto. 

 Nerinsea Rcemeri, Gold/. 

 — — yiaurgis, Bom. 

 Ceritbium limaeforme, Bom. 



Trigonia Meriani, Ag. 

 Terebratula insignis, Schiib. 

 Grlypticus bieroglypbicus, Goldf. 



It is recorded from the Kimeridge Passage-beds by Prof. Blake. 



