R. F. Tomes — Inferior Oolite Madreporaria. 445 



Cheltenham district. I have also obtained it from the Upper Coral- 

 bed in the Slad Valley near Stroud. It is now therefore obvious 

 that it has a considerable vertical range in the Inferior Oolite. A 

 specimen from Birdlip shows its method of gemmation very clearly. 

 It takes place either on the exposed margin of the wall between the 

 calices or a very little within the calice, as even when still very 

 small it is impossible to say from which calice the young one 

 proceeded. 



ISASTR^A DEPRESSA, Tomes. 



Besides the localities already mentioned in my communication 

 on Inferior Oolite Corals, I have now seen examples from the Lower 

 Coral-bed at Birdlip, and at Juniper Hill in the Painswick valley. 

 I have also a specimen which was given to me by the late Dr. 

 Bowerbank, with the information that it had come from Dundry Hill. 

 Another specimen from the same locality is in the Northampton 

 Museum. There is also one in the Museum at Oxford, which was 

 taken from the Inferior Oolite in the Hook Norton cutting of the 

 Banbury and Cheltenham Eailway. The presence of this species 

 at the latter place might lead to the conclusion that the lower beds 

 of the Inferior Oolite are not unrepresented there. 



Chorisastr^a gregaria and C. obtusa. 

 I enter with some reluctance into a repetition of what I have 

 already insisted on respecting some corals which I placed in the 

 genus Chorisastrcea. So far as the two English species, C. gregaria 

 and C. obtusa, are concerned, everything depends upon their mode 

 of increase. If it is by fissiparity, then are these species simply 

 Thecosmilians, but if accomplished by means of gemmation, some 

 other genus than Thecosmilia must be chosen for their reception. 

 Now, Professor Duncan himself, speaking of these same corals 

 (Quart. Journ. Geol. Soc. vol. xlii. p. 128), says, "An attempt was 

 made to include the well-known species of Thecosmilia, which at 

 first increase by gemmation and then by fissiparity " {i.e. to include 

 them in Chorisastrcea). The words have been given in italics by 

 me. A few pages further on (p. 113), he refers to one of my own 

 figures in proof of fissiparity in Chorisastrcea gregaria. That figure 

 represents the earliest period when increase takes place, just at the 

 time when the corallum ceases to be simple and becomes compound. 

 This, according to Professor Duncan's own words, should be the 

 period for gemmation, instead of fissiparity. The two statements 

 are of course inconsistent with each other. The real fact is, gem- 

 mation and nothing else takes place, and we have exactly the same 

 process which is represented by the figures of Chorisastrcea corallina, 

 From., C. neocomiensis, From., and C. dubia, Becker. One of the 

 figures of the latter species (from the Corallien of Nattheim) bears a 

 strong resemblance to some of the more simple examples of C. gre- 

 garia, and answers to the descriptive words of MM. Milne Edwards 

 and Haime which they applied to their Thecosmilia gregaria. They say 

 that the corallites of that species differ from those of Thecosmilia by 

 " remaining in general grouped in fasciculi to a considerable distance 



