298 R. F. Tomes, — British Cretaceous Madreporaria. 



Finally, I wish to express my indebtedness to Professor Bonney 

 for the help he has afforded me in the preparation of these notes. 



DESCEIPTION OF PLATE XII. 



Fig. 1. — General structure of glaucopliane gabbro. To the right and below the 

 centre are three crj-stals of diallage, showing the dark border of glaucophane, 

 and, internally, dark patches of the same mineral. In reality nearly all the 

 mineral is converted into glaucophane ; the orthopinacoidal striation of the 

 diallage is seen with difficulty in the figure. Above these crystals is much of 

 a pale-green chloritic mineral with flakes of glaucophane, and in places with 

 a border of the same. In it can be seen large black patches of pyrites, and 

 others of a water-clear subs-tance. Near the centre and left-hand top corner 

 are good examples of the altered groundmass. x about 8^. 



Fig. 2. — The glaucophane fringe surrounding a crystal of diallage, itself almost 

 entirely altered to the same mineral. The extension of the fringe into the 

 altered groundmass of the rock is seen to the left of the figure, x about 75. 



III. — Observations on soaiE British Cretaceous Madreporaria, 

 WITH THE Description of two New Species. 



By Egbert F. Tomes, F.G.S. 



(PLATE XIII.) 



ON the 24th of June, 1885, a paper by me, entitled "Observations 

 on some imperfectly known Madreporaria from the Cretaceous 

 Formation of England," was read at a meeting of the Geological 

 Society which, encountering an adverse report from the referee, was 

 with the consent of the Council, withdrawn by me, and published 

 verbatim in the Geological Magazine of the same year (Dec. Ill, 

 Vol. II, pp. 541-563, PI. XIV), 1885. The present communication 

 is a continuation as well as a correction of the former one, which 

 has become necessary from the acquisition of additional material. 

 Before, however, going into particulars respecting the several species 

 to be referred to here, I wish to offer a few remarks on certain of 

 the genera. 



Bathycyathiis has been merged by the late Professor Duncan into 

 Car yophj Ilia, but I am not at present prepared to accept that 

 alteration, a very strict revision of the latter genus being, according 

 to my view, quite necessary before such forms as Bathycyathiis 

 Sowerbyi are placed in it. 



Ccelosmilia, as we learn from the same authority, is a subgenus only 

 of Trochosmilia ; " the main distinction between the two types only 

 relates to the amount of endotheca." ' While, however, expressing 

 himself as above, Professor Duncan did not fail to note that Ccelosmilia 

 includes " a number of species with a well-defined facies." It is 

 that well-defined facies, with certain important peculiarities in the 

 development of the septa themselves, into the consideration of which 

 I do not here enter, that induces me to retain, at any rate for the 

 present, the genus Ccelosmilia as defined by MM. Milne Edwards 

 and Haime. 



Although no species of Smilotrochus is admitted in the present 

 paper, it is desirable that a few remarks should be made respecting 



' Eevisiou of the Families and Genera, 1884, p. 52. 



