186 



Annulosa. 

 Serpula grandis, Ooldf. Serpula Umax, Gold/. 



ECHINODEEMATA. 

 Clypeus Michelini, Wr. Pseudodiadema depressum, Deaer. 



Stomecliinus germinans, Phil. Acrosalenia Lycetti, Wright. 



In instituting a careful comparison between tlie Palaeontology 

 of this zone and that of the " Calcaires a Terebratula Phillipsii," 

 it is evident they are the true equivalents of each other ; many 

 of the fossil species are identical, and all present the general 

 facie s of the zone. 



The "Calcaires a Collyrites ringens," or "Calcaires fissiles a 

 GerviUies," are represented in the counties of Gloucester, 

 Somerset and Dorset by the zone of Ammonites ParJcinsoni, (see 

 section of Cleeve HiU, Fig. VI.) I am not aware that any 

 Collyrites have been found in these strata in the Cotteswold 

 Hills ; but in Dorsetshire Collyrites ringens and C. ovalis are 

 collected in considerable numbers, with Ammonites ParJcinsoni, 

 Amm. Martinsii, and other leading fossils of this stage, 

 so that the true relative position of the beds is determined by 

 these very characteristic urchins of the Inferior Oolite. This 

 uppermost division, or zone of Ammonites ParJcinsoni, consists 

 of — 1st, Upper Ti'igonia grit; 2nd, Gryphite grit; 3rd, Lower 

 Trigonia grit ; and 4th, Chemnitzia grit. It contains a very 

 large assemblage of fossils, which are very characteristic of 

 this stage ; several of the species which appear for the first 

 time in these beds extend throughout the Great Oolite, Forest 

 Marble, and Cornbrash. I have already stated, in reference to 

 this zone, that the fauna of the Lower Trigonia grit presents a 

 remarkable contrast to that of the freestones on which it rests. 

 Many species of Fish, Ammonites, Conchifera, Echinodermata, 

 and Anthozoa, which now appear for the first time, lived 

 through the subsequent stages and flourished in the Corn- 

 brash, in which they all died out. It is a remarkable fact that 

 the fauna of the Parkinsoni zone has many more palseonto- 

 logical characters in common with the Cornbrash than with the 

 lower divisions of the Inferior Oolite.* 



* Quarterly Journal of the Geological Society. Vol. xvi., p. 39. 



