76 THE CRAG POLYZOA. 



perhaps the anti-oral avicularium, and the narrow slit in front of the ovicell ; but as the 

 latter condition is not confined to this species, the avicularium is, of all the characters, that 

 most to be relied upon. 



3. R. NOTOPACHTS. PI. XII, fig. 4. 



Fenestris rhomboidalibus, angustis ; cellulis ovalibus immersis, seu inconspicuis, 

 aviculario rostriformi ccntrali numitis ; ostio orbiculari, infra sinuato seu inciso, supra 

 spinis duabus rnarginalibus armata, ovicellula magna, froute aperta. Ramis postice 

 convexis, superh'cie lineis transversis signata, substantia crassa sublaminata. 



Fenestrse rhomboidal, narrow ; cells deeply immersed, oval, or inconspicuous ; orifice 

 orbicular, with a sinus below, and a marginal line on each side above ; a prominent 

 avicularium on the front of the cell in the centre; ovicell large, open in front; dorsal 

 surface convex, marked with deep, usually transverse, lines ; substance of branches 

 behind very thick, laminated. 



Habitat. Q. Crag, in a hollow in a mass of Cellepore, J. S. S. 



The peculiarly thick aspect of the polyzoarium, and the comparatively small fenestrse 

 distinguish this species at first sight, but it is characterised more especially by the extra- 

 ordinary thickness and density attained by the calcareous substance on the back of the 

 polyzoary, and which is disposed in crescentic laminae. 



Although unable to refer R. notopacliys to any other fossil or recent species, it should 

 be remarked that an undescribed recent form, strongly resembling it in some respects, 

 exists, but whose habitat I am not certainly acquainted with, though believing that it is 

 from the Mediterranean, or some part of the Coast of Spain. The only fragments of this 

 and the following species yet met with are too imperfect to convey any notion of its 

 general form. 



4 R. SIMPLEX (n. sp.) PI. XII, fig. 3. 



Fenestris ovalibus angustis acutis ; cellulis alte immersis, subovalibus ; subinde poro 

 unico centrali ornatis ; ostio orbiculari infra sinuato, supra spinis duabus ruarginalibus 

 munito ; superficie ramorum dorsali glabra vibicata. 



Fenestrse oval, narrow, pointed at each end ; cells deeply immersed, or obscurely oval ; 

 orifice orbicular, with a sinus below, and a spine on each side above ; dorsal surface 

 smooth, vibicate ; sometimes a pore in the centre of the cell in front. 



Habitat. C. Crag, S. Wood. 



This species, if really distinct from the preceding, which is doubtful, appears to be dis- 



