R. F. Tomes — Inferior Oolite Madreporaria. 447 



and the other by having a subdendroid form. For the present I 

 leave them where they are, but must enter my earnest protest against 

 there being any near affinity with Sijmpliyllia in the Oolitic form 

 now under consideration. 



Phyllogvra sinuosa, Tomes. 



I have lately met with several examples of this species in the 

 Lower Trigonia Grit near Cheltenham, but in no instance in the 

 Coral-bed at Crickley. It has not, indeed, been observed in the Lower 

 Coral-bed at any locality, though it most frequently occurs in the 

 Oolite marl, or third Coral layer. 



Platastr^a endothecata, sp. nov. (Plate X. 1 Figs. 1, 2, 3, 4.) 

 Clausastrcea Conybeari, Tomes, Proc. Geol. Assoc, vol. vi. no. 4. 



The present species, the occurrence of which I have already 

 recorded, under the name of Clausastrcea Conybeari, must, with the 

 allied species from the Great Oolite of Bath, be referred to the new 

 genus Platastrcea. Specimens from the Inferior Oolite of Hook 

 Norton are for the most part fairly preserved, and sometimes when 

 broken through, show the structure of the septa and the dissepi- 

 mental tissues very clearly. 



The corallum is rudely lenticular, and not very large. The upper 

 surface is moderately convex, sometimes almost flat, and never much 

 elevated, and the outer mai-gin is rather thin, but rounded rather 

 than angular. The under surface is much more prominent than the 

 upper surface, in some specimens almost subpeduncular, with a 

 central point indicating a former attachment. The common or 

 basal wall is rudimentary, and has intermittent and narrow rings 

 of epitheca. The radiating mural costse are thin, and the spaces 

 between them are wide and filled with dissepiments. The calices 

 have a more or less quadrangular or rounded outline, and are shallow. 

 The septa are all of them continuous with those of other calices, but 

 they often form an angle where they meet and unite between the 

 calices. They are very stout over the mural region, but speedily 

 become thinner as they approach the visceral cavity. The margins 

 of all of them are denticulated, the teeth consisting of rather large, 

 regular, and rounded tubercles, the greater diameter of which is 

 across the septum. There are four cycles of septa in six systems. 

 In some systems the fourth cycle is incomplete, while in others there 

 are a few very rudimentary septa of the fifth cycle. 2 The primary 

 septa extend to the fossula and meet, the secondary ones are very little 

 shorter than the primary ones, and those of the tertiary cycle are 



1 This Plate was published in the September No. with the first part of this paper. 



2 I must differ wholly from Prof. Duncan when he says that there are never two 

 rudimentary cycles in the same calice. There are not ever, to the best of my know- 

 ledge, two rudimentary cycles in the same system, but there maybe, and often are, in 

 the irregularly developed calices of Jurassic M adeporaria, rudimentary septa of quite 

 different ages in different systems. The third cycle may be rudimentary in one and 

 complete in another, in which a fourth may have even commenced its growth. Such 

 irregularities are frequent after recent rejuvenescence, one side of the calice havino- 

 perhaps the full complement of septa, while the other may have only the earlier 

 developed cycles. 



