MEMBRANIPORID.E. 33 



Cells ovate, broader below ; no lamina ; margin granular, thin ; from four to six oral 

 spines above. Avicularia dispersed, sometimes one on each side of the ovicell. 



Fldstba Pouilletii, Audouin, ExpL, p. 240; Savigny, Egypt, pi. ix, fig. 12. 

 M. Pouilletii, Alder, Transact. Tyneside Nat. Field Club, p. 56, pi. viii, fig. 5. 



Habitat. — C. Crag, on shell, S. W. {Recent) Britain; Mediterranean. 

 A very small fragment only has been observed, but with the characters so well displayed 

 that little doubt can be entertained of its identity with the recent form. 



7. M. RHYNCHOTA {;n. sp. F) PI. Ill, fig. 7. 



Polyzoario radiatQ ; superficie glabra ; apertura magna, oblonga, deorsum latiori ; 

 margine incrassato, spina (articulata ?) uno latere armato. Aviculario cylindrico ascendente, 

 in fronte cellulse posito. Ovicellula exigua, fossa triangulari signata. 



Polyzoarium radiate ; surface smooth ; aperture large, oblong, wider below, margin 

 thickened ; a small marginal spine (probably articulated) on one side, about one third of 

 the length of the cell from above ; a prominent, cylindrical, ascending avicularium on the 

 front of the cell below. Ovicell small, with a triangular fossa in front. 



M. TRi FOLIUM (? var.) (S. W. 



Habitat. — C. Crag, on shell, often overgrowing species of Lepralia or Membranipora 

 trifolium. S. W. 



The form of the aperture, and the position and presumed articulation of the marginal 

 spine, give this form some resemblance to M. Flemingii, in which occasionally a 

 single, very large, articulated spine may be observed on one side only of the aperture 

 {vide ' B. M. Cat.', pi. Ixxxiv, fig. 3). But in other respects, no relation whatever exists 

 between the two. The long and strong cylindrical avicularium on the front of the cell, 

 and which is very rarely absent, affords an easy diagnostic character to this species. 

 When the ovicell is developed, as it appears in most cases to be, the avicularium of the 

 cell above is elevated, as it were, by the rising ovicell of the cell below, which thus comes 

 to be crowned, and in fact almost concealed, by the avicularium. 



8. M. APERTA (//. ,9J».) PI. Ill, fig. 13. 



Polyzoario effuso, reticulari ; cellulis apertis ; margine superne elevato, glabro ; avicu- 

 lariis magnis, elongatis, lanceolatis, inter cellulas dispositis. 



5 



