Vol. 52.] 



A DELIMITATION OF THE CENOMANTAN. 



167 



occurring in the Lower Chalk is a little larger than that occurring 

 in the Warminster Greensand. We do not, however, rely greatly 

 on this method of comparison ; as already mentioned, it is to 

 the cephalopoda alone that we look for reliable palaeontological 

 evidence regarding the age of such different deposits. Now the 

 Cenomanian cephalopoda in our list number 14 ; of these only 7 

 occur at Warminster, while all of them occur in the Lower Chalk. 

 Further, of those in the Warminster Greensand all except three 

 (Ammonites varians, A. Coupei, and A. falcatus) are rare fossils, 

 while in the Lower Chalk nearly all are very common. This evidence 

 is very strongly in favour of the view for which we contend, and its 

 force will be further alluded to in the sequel. 



Porifera (Sponges). 



Corynella rugosa, Hinde 



,sp ••• 



Elasmostoma consobrinum, d'Orb. 



„ plicatum, Hinde 



Trematocystis siphonioides, Mich. , 

 „ d'Orbignyi, Hinde , 



Jerea, sp „ , 



Pachypoterion compactum, Hinde . 



Plocoscyphia, sp. (fragments) 



Stauronema Carteri, So lias 



Hydrozoa. 



Porosphara urceolata, Phil. . . 

 „ sp 



ACTINOZOA. 



Micrdbacia coronula, Goldf. 



Annelida. 



Ditrupa diffbrmis, Lain 



Galeolaria filiformis, Sow. ... 

 „ plexus, Sow. 



Crustacea. 



Scalpellum 



Normandy. 



A B 







■2 o 

 ►> p 



England 



D E 



§0 



