114 THE CRAG POLYZOA. 



irregular patches, it would hardly appear that the two could be identical. But there is 

 another form still existing in our seas of which no account seems yet to have been given, 

 whose aspect, in some respects, far more nearly approaches that of D. simplex, though 

 differing in the important particular that the upper side of the tubes is distinctly 

 perceptible and depressed, or even channelled, whilst in D. simplex what is visible of that 

 surface is convex and even. 



One or two tertiary fossil species approaching the present in some respects are tigured 

 by Reuss, and one in particular, D. flabellum (op. c. pi. vii, fig. 9) might almost be 

 regarded as a variety of it. The identification, however, is far too uncertain to justify 

 its adoption at present. 



Genus 8. Patinella, Grai/ [subg.). 



Polyzoario disciformi, concavo. Cellulis ad marginem disci ascendentibus, orificio 

 simplici, orbiculari ; superficie Integra, glabra, subinde obscure annulata. 



Disc concave or depressed in the centre ; tubes ascending towards the margin ; mouth 

 simple, circular; surface not perforated. 



Madrepora (sp.), Linn. ; Pallas ; Olivi. ; Esper. 



MiLLEPORA (sp.), Ellis and Solnnder. 



DiscopoRA (pars), Fleming {not Lamarck) ; Busk, Brit. Cyclop., art. " Polyzoa," p. 16. 



TuBULiPORA (pars), iamarcA; Milne-Edwards; auct. 



Patinella, Gray, Supplement to List Brit. Rad., p. 137. 



RuBULA (?), Befrunce. 



RosACiLLA (? pars), Roemer. 



DiscosPARSA (sp.), D'Orbigny. 



1. P. PROLIGERA, {71. Sp.) ? PI. XIX, fig. 1 ; PI. XX, fig. 3. 



Sessilis; cellulis plerumque coalitis, ad centrum tantiim subinde ex parte hberis ; 

 disci margine supra prolifera. 



Polyzoarium sessile ; tubes rarely distinct and only towards the centre ; cellular border 

 wide and thick, proliferous from the upper surface. 



Habitat. — C. Crag, S. Wood. 



The only species bearing any resemblance to the present in its peculiar proliferous habit 

 is one named by M. D'Orbigny (' Terr. Cret.,' pi. Dcclvii, figs. 5 — 10) Discosparsa 

 marginata. His Semimultea cupula (ib. pi. Dccxli, figs. 1 — 4), appears also to throw out 

 buds from the upper surface, but more from the centre than towards the margin. With 

 these exceptions I have been unable to find a similar condition in any other form. 



