OX FOSSIL rOLYZOA. 149 



Family IV. LlCHEXOPOBIAS, Smitfc. 



= DiscoporiJiv, Busk, ' Brit. Cyclop.' ; Discnporettido?, Busk, ' Mr.s. Cat.' 

 pt. iii. ; Gaveidm, (part) D'Orb. ; Tubigeridce, (part) D'Orb. 



' Zoarium discoid, simple or composite, adnate, or partially free and 

 stipitate. Zooeela tubular, erect or suberect, disposed in more or less 

 distinct series, which radiate from a free central area ; the intermediate 

 surface cancellated or porous.' — Hincks, p. 471. 



Whether this family will remain intact as we get a more perfect 

 knowledge of the structure of the fossil forms below the Tertiary rocks, I 

 am, at present, unable to say. It would be unwise to displace the 

 Tertiary forms that would naturally fall under this head, and the few 

 Mesozoic species known to me may also find a resting-place here, for 

 unless we knew more of the structure of the Jurassic species it would be 

 also unwise to disturb the placement of these ; but when we come to the 

 few disc-like forms of the Palaeozoic rocks, we meet with peculiarities of 

 structure unknown to me in the more recent I&chenoporidce. Three 

 species are described in the ' Silurian Sj-stem ' as Discopora, and figured 

 in Plate 15 of that work (figs. 21, 22, 23) ; these are named : — 



Discopora antiqua, Milne- Ed. r — Cellepom antiqua, Goldf. 



Membranvpora ,, Blaiuv. 

 „ sqitamata, Lonsdale 

 ,, ? favosa ,, = Cellepora favosa, Goldf. 



Within the last few years the affinities of these forms have been the 

 subject of a good deal of controversy. Dr. Gustav Lindstrom ('Ann. 

 Mag. Nat. Hist.' Ser. 4, vol. xviii. p. L and seqnel), in speaking of the 

 development of Monticulipora petropolitana. Pander, says that — ' It 

 begins .... as a Bryozoon, as a Discoporella, or, as what Hall has 

 termed Ceramopora imbricata (' Pal. N. Y.' vol. ii., p. 169, pi. xl., figs, 

 la-li). There can be no doubt that this is closely allied to the recent 

 Discoporella. (See Fr. Smitt, 'Ofv. Vet. Akad. Forb. 1866,' p. 470, pi. xi. 

 fig. 4).' This opinion has been contested by Prof. Nicholson in his 

 work on the ' Tabulate Corals,' p. 283, wherein he says — ' I have en- 

 deavoured to give a faithful account of the views Dr. Lindstrom ha-', 

 published as to the development of the Monticulipora, and upon which he, 

 in large part, bases his view that the fossils of this genus are really 

 Polyzoa.' Since the publication of the works 'Monticuliporidaj ' and 

 ' Tabulate Corals ' of Prof. Nicholson, Mr. John Young, of Glasgow, has 

 'discovei'ed specimens of another Biyozoon, or Polyzoon, as I prefer 

 to name it ... . that is closely allied to the Silurian Ceramopora, 

 and which I have been enabled to follow clearly in all its stages of 

 growth until it becomes a true Monticulipora ' (' On the Identity of Cera- 

 mopora megastoma,' &c, 'Ann. Mag. Nat. Hist.' Dec. 1882). The stages 

 through which this form passes before it assumes the Monticulipora form, 

 are similar to, or probably the same as, the stages indicated by Dr. 

 Lindstrom — the Fistulipora and Thecostegates stages. Mr. John \'oung, 

 however (Joe. cit. p. 430), does not commit himself to give an opinion on 

 'the vexed question as to the zoological position of the organisms showing 

 these changes, but only states that, as regards the Carboniferous form, one 

 of two things seems certain, viz., that if Fistulipora minor (M'Coy) be 

 held to be a tabulated coral of the Moniiculiporidce group, then Ceramo- 



