R. F. Tomes — British Cretaceous Madreporaria. 303 



Crratotroohus insignis, Duncan, sp. 

 Smilotrochus insignis. Dune. : Supp. Brit. Fos. Cor., 1870, pt. ii, No. 2, 

 p. 37, pi. xii, fig. 17; pi. xiv, fig. 18. 

 There is considerable doubt as to the generic place of tliis small 

 species, but that it cannot retain its position in the genus Smilotrochus 

 is most certain. In addition to the existence of a very distinct 

 columell<a it is pi'obable that there is a ring of pali, in which case it 

 is a Trochocyathiis. In fractured specimens there is to be seen 

 surrounding the large columella a kind of outer ring having much 

 the appearance of adherent and st3'liform pali, which, however, 

 have a height corresponding with that of the columella, and may 

 therefore be a part of it. 



DiBLASUS, sp. 



By the kindness of Mr. Jukes-Browne I have examined some 

 much worn specimens of Diblasus from the Coprolite Bed of the 

 Cambridge Greensand, and compared them with examples of Diblnsus 

 Grovensis from the Chalk of Gravesend. They are certainly 

 specifically distinct, the cost;© being small — only half the size of 

 those of D. Gravensis — and much more regular in size and 

 prominence. In none of the specimens are tliere any calices, and 

 I refrain from further description. 



Placosmilia tdbkkosa, Edw. & Haime, sp. 



Tarhinolia compressa, Morris: Cat. Brit. Fos., 1843, p. 46. 

 Trochosmilia ?, Inherosa, Edw. & Haime : Brit. Fos. Cor., 1850, p. 58, 



pi. X, fig. 2. 

 Trochosmilia tuberosa, Morris : Cat. Brit. Fos., 2nd ed., 1854, p. 68. 

 Smilotrochus tuberosa, Edw. & Haime : Pol. Fos. Paleoz., 1851, 



p. 29; Hist. Nat. Cor., 1857, torn, ii, p. 71. 

 Placosmilia cimeiformis?, Duncan (not Edw. & Haime) : Supp. Brit. 



Fos. Cor.. 1869, pt. ii. No. 1, p. 27, pi. x, figs. 1-5. 



A single specimen from the Greensand of Blackdown, which 

 formed part of the collection of my late friend Dr. Wriglit, and is 

 now before me, has the peculiar swellings near the foot which gave 

 to the species its specific name ; and although they are not quite so 

 conspicuous as in the figures given by MM. Milne Edwards and 

 Haime, there is no doul)t as to the species. 



The Blackdown specimen has a deep-seated and not very strongly 

 formed columella, extending the whole length of the fossula, 

 which is more than half the length of the calice, and its presence 

 removes the species at once into the genus Placosmilia, and confirms 

 its specific identity with the small deltoid corals from the Haldon 

 Greensand regarded by Professor Duncan as the Placosmilia cunei- 

 formis of MM. Milne Edwards and Haime ; a wholly distinct and 

 dissimilar species occurring in the Gosau deposits, as I have 

 determined by the comparison of undoubted specimens from the 

 last-named locality. 



The Haldon specimens correspond very closely in general size 

 and form with the one from Blackdown, and especially in the length 



