ESCHARID^. 63 



b. Layers readily separable. 



3. Biflustra. 



2. Cells in a single layer. 



a. Reticulate. 



4. Retepora. 



fj. Continuous. 



.5. Hemeschara. 



Genus 1. Eschara, Bay. 



Polyzoario erecto, foliaceo, integro vel subdiviso, sive e ramis angustioribus aut 

 latioribus composite, cellulas in utraque facie gerente. Cellulis decumbeutibus, quinciiii- 

 cialibus, in seriebus longitudinalibus dispositis. Lamellis conjunctis. 



Polyzoarium erect, foliaceous and expanded, or ramose and lobate, with wide or 

 narrow divisions. Cells decumbent, disposed in longitudinal series quincuncially on both 

 surfaces ; the layers inseparable. 



EsCHAKA (pars), Ray; Ellis ; Pallas; Lamarck. 



— Johnston; D" Orbigny ; Hag enow ; lieuss ; M. Edivards ; Busk, &c. 

 Flustra (pars), Lmn. 

 MiLLEPORA (pars), Solander. 

 Cellepora (pars), Esper. 



The characters above given are sufficient to distinguish all the species of this genus in 

 their complete or mature condition ; but it must be remarked, that as in the case of 

 Flustra foliacea, so in some species of Eschara, the polyzoarium sometimes, in fact usually, 

 as it would seem, spreads out into an adnate crust on the surface of the stone or shell 

 upon which the growth is affixed. Detached portions of such a crust are indistinguishable 

 from a LepraUa, and it is not improbable that this mistake has been often made, and it is 

 one to which the paleontological observer is peculiarly liable. 



The genus Eschara is naturally subdivided into two sections, which though running 

 into one another, are usually sufficiently distinct for all practical purposes. In one of 

 these divisions the polyzoarium is broad, expanded and foliaceous, variously folded and 

 contorted, but not subdivided into distinct lobes. Of this division E. foliacea affords a 

 good type. In the other division the polyzoary is divided into branching lobes of various 

 forms, and differing considerably in width in different species — sometimes broad, short, 

 and expanded, sometimes constituting narrow or even ligulate branches, occasionally so 



