TUBULIPORIDyE. 109 



though still minute appear to be larger than in most other species where the same kind of 

 porosity also exists. The outlines of the cells are shown through the deposit by dark- 

 coloured, transparent lines, which give the surface a peculiar and very characteristic 

 aspect. 



Genus 4. MESENTERIPORA, Blainville. 



Polyzoario foliaceo ; cellulis in stratis duobus lamina media calcarea sejuuctis dispositis 

 et ad utramque faciem spectantibus. 



Polyzoarium foliaceous ; cells in two layers parted by a calcareous septum and 

 opening on both surfaces. 



MESENTERIPORA, Blainville, Man. d' Act., p. 432; IfOrbigny; S. Wood. 



DIASTOPORES BISERIALAIRES, M. Edward*, ]. c., p. 40. 



DIASTOPORA (pars), Lamouroux ; M. Edwards; Hagenow ; Reuss ; Michelin. 



BIDIASTOPORA (pars), D'Orbiyny. 



DITAXIA, Hagenow, Maast. Kredeb, p. 49. 



CERIOPORA (pars), Gohlfuss. 



The expanded or foliaceous Cyclostomata are subdivided by Milne-Edwards into two 

 great groups, distinguished by the character that in the one the tubes are almost wholly 

 immersed and in the other partially free. To the former group he applies generally the 

 appellation " Diastopores," and to the latter that of ' : Tubulipores. 3 ' This division is 

 natural, but it seems convenient that it should be carried still further, and in the doing of 

 this with respect to the " Diastopores " no better classification can be adopted than that 

 suggested by the same author, viz. into 1. "Diastopores simples " 2. D. enveloppantes ; 

 3. D biserialaires. The groups thus formed, which may be regarded as of generic value, 

 having to be provided with names it does not appear difficult to fit them with appropriate 

 appellations from those already in use, as applied to some of the species, and thus to avoid 

 the necessity of burdening science with new terms. I propose, therefore, to term the 

 simple Diastoporse of Milne-Edwards, Diastopora ; the enveloping, or laminated forms, 

 Berenice!} ; and the biserial, Mesenteripora, under which of course will fall Ditaxia 

 of Hagenow. 



1. M. MEANDRINA, 8. Wood. PL XVII, fig. 2 ; PL XVIII, fig. 4; and PL XX, fig. 2. 



Subglobosa, cavernosa, varie flexuosa seu contorta, laminis coalescentibus. 

 Polyzoarium subglobose, cavernous, foliations contorted, anastomosing. 



