Heiiews — The Jurassic Rocks of England. 



133 



It has generally been considered that the Lower Kimeridge of 

 Dorsetshire represents in the main the " Virgulien " of foreign 

 authors, and casts of Ex. virgula are said to have been found as low 

 down as the Abbotsbury iron-ore. But Mr. Woodward finds this 

 fossil, together with Am. longispinus, also in the Upper beds. These 

 latter, between 600 and 700 feet thick in some places, are 

 exceptionally developed in Kimeridge Bay and throughout the Isle 

 of Pur beck, where the dark bituminous and paper shales of 

 Chapman's Pool, etc., charged with Lucina minuscula and Discina 

 latissima, are of immense thickness. The most curious feature of 

 the whole is that, although there is a complete sequence between 

 these clays and the Portland beds of St. Albans Head, yet the so- 

 called Middle Portlandian fauna of Swindon and Hartwell has not 

 yet been discovered in that locality. 



Kimeridge Clay. 



Away from the coast we are mainly dependent upon brickyards, 

 etc., for our knowledge of the Kimeridge Clay, so that the divisions 

 cannot be made out with certainty in all places. Of course it is 

 obvious that the fauna of Hartwell, for instance, differs entirely 

 from that of Eingstead Bay, although for purposes of mapping both 

 are included in the Kimeridge Clay. We quite agree with the 

 author that " it is not possible to be consistent in all our dealings 

 with these formations without detailed and long-continued hunting 

 for fossils." Even then much remains to be explained. 



In the East Midlands the observations of Blake have been sup- 

 plemented by those of Roberts, and it is to the palajontological 

 researches of these writers that we are indebted for most of our 

 knowledge of the Kimeridge Clay in the counties of Cambridge, 

 Norfolk, and Lincoln. In the Isle of Ely, Roberts recognized 15 ft 

 of Upper Kimeridge with Discina latissima and Exogyra virgula, 

 and 80ft. of Lower Kimeridge with Ammonites alternans, Astarte 

 Bupracorallina, and Ostrea deltoidea. It is noteworthy that here 

 Exogyra virgula is regarded as an Upper Kimeridge form. 



Portland Beds (Portlandian). — Declining to accept the term 

 " Bolonian " for any of these beds, Mr. Woodward adopts the 

 following grouping : — 



Upper Portland Beds .... Portland, Tisbury, and Swindon Stones. 



Lower Portland Beds .... Portland Sand, Swindon and Hartwell Clays. 



He further remarks that the zones of the Portland beds most 

 generally adopted are those of Am. giganteus and Am. gigas, the 



