ESCHARID.E. 71 



of the mouth is a raised line, the two meeting towards the lower part of the cell, also a 

 particular in which M. Charlesicorthii agrees with some Salicornaritf. Another point in 

 which this agreement is perhaps still more manifest, is in the condition of the ovicell, 

 which is itself, as in that genus, quite inconspicuous, though its orifice is manifest enough 

 in a crescentic, or rather horse-shoe-shaped fissure, immediately within the angle which 

 forms the summit of the cell-area. This opening is usually much enlarged by attrition or 

 fracture, and then appears as a rounded orifice of considerable size. 



Dispersed irregularly among the other cells, and apparently breaking their uniformity 

 of arrangement, are smaller areas of irregular shape, containing an elongated, curved 

 falciform opening. These are obviously large avicularia, which in this case replace the 

 true cells, and do not belong to any individual cell. Many instances of a similar 

 arrangement of avicularia exist also among the extinct Eschars, especially among those 

 belonging to the Cretaceous period. 



Genus 3. BIFLUSTRA, D'Orligny. 



Polyzoario foliaceo seu ramoso ; cellulis apertis, marginatis, quincuncialibus, in utraque 

 superficie in seriebus longitudinalibus dispositis. Lamellis, seriebusque cellularum facile 

 disjungendis. 



Polyzoarium foliaceous or ramose ; cells open in front, with a distinct raised border, 

 disposed quincuncially on both surfaces in longitudinal series. The two layers of cells 

 readily separable, as are also the longitudinal series. 



BIFLUSTEA, D'Orbigny, Kecherches sur les Moll. Bryoz., Ann. d. S. Nat., 3d ser., xviii, 

 p. 330. 



M. "D'Orbigny observes that his genus Biflustra stands in the same relation to Mem- 

 branipora that Eschara holds with respect to Cettepora (Lepralia) ; that is to say, that it is 

 composed of free Membraniporee applied back to back. He also states that there are both 

 living and fossil species, and that the former inhabit deep water in both hot and cold 

 regions; one species coming from Newfoundland, and a second from the seas around 

 Manilla. The only living form, however, with which I am acquainted, referrible to this 

 genus, is one from Australia, and probably, therefore, identical with that from Manilla, 

 alluded to by the French observer. It appears, so far as I know, not to have been 

 described ; and as it is in all respects identical with the Crag Fossil, it must be regarded 

 as of considerable interest. 



It forms large foliaceous, cavernous masses, of a beautiful white aspect, and exceed- 

 ingly light and fragile. The polyzoarium is composed of very regular quadrangular cells, 

 with granular margins, and widely open in front, whilst behind they are closed by a 



