92 rKOCEEDINGS OF THE OEOLOGICAL SOCIETY. [DeC. 6, 



and in the Sutton species. So alike are the di'awing and the 

 specimen that it might he asserted the one was taken from the 

 other. 



The genus Elyastroea descrihed hy Laube is new, and not known 

 out of the St. Cassian strata ; it is allied to the Mesozoic genera He- 

 liastrcea, Isastrcea, and Prionastrcea, and it has some faint trace of the 

 double-wall arrangement of many Palaeozoic genera. Ueliastrcea and 

 Prionastrcea flourished in the Oolitic and Cretaceous periods, and are 

 still represented in the existing coral fauna, but Isastrcea was a St. 

 Cassian genus, and lasted until the Ealunian epoch. The discovery of 

 the genus which unites all these sufficiently to make their generic 

 distinction doubtful, is very important, and that it should occur so 

 low in the Mesozoic series is very suggestive. The species Fischeri 

 is a bulky form, with very irregular calicos, and is represented in 

 the Sutton Stone by a large specimen partly polished. 



The most common coral in the collection is one which has a broad 

 base and an undulating gibbous surface, covered with small geo- 

 metrical calices. This is the commonest form ; but another is equally 

 large as regards its base, and has a flat upper surface covered with 

 calices, like the gibbous form. There is not a speciflc difference. 



A third form covers, like a parasite, part of the surface of 

 the Plicibclophyllia i^econdita ; the calices are smaller than in the 

 other forms ; but they are all essentially alike. It is remarkable 

 that the Hhabclophyllia in its St. Cassian habitat is covered by a 

 parasitic sponge. 



The three varieties of Astrocoenia Oppeli are judged to be such 

 because the minute anatomy of the calices is alike in air cases, and 

 that the habit of growth of the type is not sufficient to enable it to 

 assume a specific diff'erence. It is a pity that Laube had not the 

 larger Sutton variety for the type ; but he has the right to have the 

 three forms referred to his by priority of description, I have named 

 the varieties — 



1. Gibbosa, ] 2. Plana, 



3. Parasitica. 



The genus is well known in the Lower Cretaceous, Eocene, and 

 Miocene coral faunae, but has not been found hitherto in Jurassic 

 deposits. 



The Montlivaltia from the Sutton Stone is a stunted, multiseptate 

 form, with a ridged epitheca; it resembles the general type of that 

 section of the genus which is almost peculiar to the St. Cassian 

 coral fauna. The casts of it are common, but the specific deter- 

 mination is impossible. 



EXPL^J^ATION OF PLATES III. & IV. 



Illustrative of the Bhcstic Fossils of South Wales. 

 Plate III. 



Fig. 1. Ostrca multicostata, Mnnst Sutton and Southerndown series. 

 2. Icsvis, Tawn. Sutton series. 



