706 



ZOOPHYTES. 



species, the Marginop&ra vertebralis, which is a simple, delicate disk, 

 about three-fourths of an inch in diameter, and about two-thirds of a 

 line thick. (Plate 60, fig. 8.) 



A singular variety (plicata] is represented in figure 9 a, b, of the 

 same plate, which may possibly be only a more advanced state of 

 Quoy and Gaymard's species, though very distinct in appearance. 

 Instead of a simple flat disk, it is in part double, and the two portions 

 are in folds, and coalesce at intervals. Many specimens of both these 

 varieties are contained in the Expedition collections. 



, Bliiinv., Man. d'Actinologie, 41<!, pi. 



M. vertebralis, Quoy and Gaymard, Voy. 

 de 1'Astrolabe. 



69, fig. 0. 



GENDS POLYTREMA. Risso. 



Pumilce; incrustantes aut subramosce, interdum lacerato-divisce. Corolla 

 subporosa, super fide punctata, cettis poriformibus minutis, sparsis, ir- 

 regularibus, scepius margine laceratis, sive immersis, sive ad pustulos 

 ekvatis. 



Small; incrusting or subramose, sometimes lacerato-subdivided. Co- 

 ralla somewhat porous; surface punctate, and with scattered, minute, 

 poriform cells, irregular, and having usually a lacerate margin, 

 either immersed or at the summits of rounded or spiniform eleva- 

 tions. 



The colour of these incrusting species is usually some shade of 

 deep red. They seldom exceed an inch in breadth, and one-third 

 this in height, and have either a smooth, minutely pustulate, or a 

 lacerate surface, and the prominences are often ragged at tips. The 

 cells have no regular shape, and no lamella within, and are placed 

 without order over the surface; and in the smoother varieties are 

 often confined to near the growing margin. 



There is little reason to believe these species to be true zoophytes. 

 They should probably be removed to the vegetable kingdom, near 

 Nullipores, or the sponges. 



The genus Polytrema was instituted by Risso for the Millepora 

 miriiacea, of preceding authors. 



