G. E. VINE C^' THE EAMTLY DIASTOPOKID.E. 359 



■cell-walls, the interspaces being occupied b}* fine tubuli. In size 

 and shape the American species do not differ verj^ materially from 

 the Dudley Berenicea ; but in Nicholson's C.ohioensis'^' we obtain an 

 altopjether new feature. The cell- arrangements of figs. 7 and 7 a are 

 similar in character, when favourably selected, to those of Carbonife- 

 rous species. The true type is seen in figs. 7c and 7 d. In these figures 

 " the cells appear in the form of rounded oval apertures, arranged 

 in diagonal rows, but separated by a vast number of small rounded 

 foramina, which appear to be the mouths of interstitial tubuli. In 

 this condition the fossil presents much the appearance of certain, 

 species of Chcetetes (MoHtiadij)ora)" f. This is a Silurian form from 

 the Cincinnati group. The C. incrustans of Hall has a nodulose or 

 tuberculated surface ; and in the C. liuronensis,lsie\io\^on, the surfaces 

 between the cells are smooth, but the cells are distinctly separated, 

 and the generic character of the species is well marked in the 

 pores. 



All these species are comparatively small in the apertures when 

 compared with the Berenicea megasioma of M'Coy, of the Carboni- 

 ferous formation (PI. XIII.). This species is more closely allied to 

 Ceramopora than to Berenicea. The patches vary in size from one 

 quarter up to nearly three quarters of an inch in diameter. The 

 patches radiate from a centric or excentric point. The cells toward 

 the centre are depressed, the cell-mouths are raised, having a circular 

 form when worn, triangular when pretty perfect. The cells have a 

 pyriform appearance, best seen in worn specimens ; but when thin 

 sections are made for microscopic study, the pyriform character is 

 seen better still, and the interspaces are filled with what Nicholson 

 calls " interstitial tubuli." In addition to these observations I can- 

 not do better than conclude this description with a few remarks by 

 Mr. John Young on this species : — ^.^ Our specimens show the cha- 

 racters of M'Coy clearly ; but I have been fortunate in finding in 

 the shales of Capelrig, East Kilbride, examples of the species show- 

 ing, besides, that the perfect cells were closed by a thin calcareous 

 cover, pierced by a narrow slit or opening, just under the raised lip 

 of the cell, and, further, that amongst the cells there is a minute 

 ceUular structure, best seen in slightly worn specimens "J. In this, 

 as Avell as in other respects, the Capehig species differs from the well- 

 preserved specimens from Hairmyres ; and in one of my specimens 

 ^ secondary disk rises, or, rather, covers a portion of the primary one. 

 The arrangement of the cells and the thin calcareous surface-cover- 

 ing are also difi'erent. It appears, therefore, that we have in our 

 Carboniferous Limestone series two distinct species instead of one. 



The Secondary forms of the Diastoporida) approach nearer to the 

 Kecent than to the Palaeozoic ; but on these I have already expressed 

 my opinion. 



It is clear, then, from aU that has been said, that the Palajozoic 

 representatives of the family Diastoporidse differ very materially from 



* Ann. & Mag. Nat. Hist. 1875, vol. xv. pi. xiv. figs. 7-7 f?. 



t Ibid. p. 188. 



\ Newspaper report. Address to the Geol. See. of Glasgow, Oct. 1870. 



