On the Elstvorth Rock and associated Strata. 109 



The Belemnites are hastatus and tornatilis, both of which occur 

 in the Oxford Clay below, but neither, so far as I have collected, 

 in superior beds. The hastatus is an inflated variety. 



The Gasteropoda are Pleurotomaria reticulata, a fossil of the 

 Calcareous Grit and Kimmeridge Clay in England and of the 

 Oxford Clay in France, being identical with the Pleurotomaria 

 Miinsteri of D'Orbigny ; Pleutomaria amphicelia, a new and pe- 

 culiar species resembling the Inferior-Oolite P. ornata ; Littorina 

 pei^ornata, a new form intermediate between the Inferior- Oolite 

 L. ornata and the Corallian muricata (I believe that it occurs in 

 the Coral Rag, Calcareous Grit, &c.) ; a new species of Littorina, 

 a new Cerithium, and a Phasianella. 



The bivalves are extremely numerous, and the new species 

 many. A few only need be given now. Among the new spe- 

 cies are Avicula pterosphena and Gryphaa elongata. Among the 

 known species are Pecten fibrosus (including ?;«^«ws)j Terehratula 

 ornithocephala, T. perovalis, and T. sphceroidalis ; Pecten lens and 

 Pecten vimineus ; Gryphcea dilatata; Lima pectiniformis ; Avi- 

 cula eocpansa, A. ovalis, and A. elliptica-, Trigonia costata, and a 

 slight variation of Dr. Lycett's variety decorata of Trigonia da- 

 vellata ; Astarte ovata, A. lurida, Opis Phillipsii, and a variety 

 of Myacites recurva. Although most of these species occur in the 

 Coral Rag and Calcareous Grit, I think, when the circumstances 

 already pointed out are remembered, and also that many Coral- 

 Rag forms range down to the Cornbrash, the fossils will be re- 

 garded as far more closely linked to the beds below than to the 

 equivalents of strata above. When one remembers the super- 

 position, I see no ground whatever on which the conclusion need 

 be disputed ; and therefore the Elsworth rock will be placed as 

 about the highest zone of the Oxfordian series. 



There are, then, in this district at least three well-marked 

 rocks dividing the Oxford Clay, to the different- zones of which 

 it will be necessary to apply distinctive epithets when the whole 

 succession shall be satisfactorily elucidated. It would be beyond 

 the object of this paper to add anything further on either the 

 rocks or clay zones ; but as it has already been mentioned that 

 the Upper Elsworth rock differs somewhat in fossils from the 

 lower bed, it may be remarked that the circumstances which 

 most attract attention are the presence in the upper band of 

 numerous masses of SerpulcE, a difference in the Brachyurous 

 Crustacea, in the spines of Cidaris, in the enormous size of Gry- 

 phcea dilatata (some being II inches long), the absence of Gry- 

 ph(2a elongata, the presence of plates of a Star-fish, the greater 

 abundance oi Littorina per ornata and of Pleurotomaria reticulata, 

 species of Perna, many Ostrece gregarice. 



These distinctions may be but local, but in this locality they 



