104 THE CRAG POLYZOA. 



the sulci usually diverging obliquely from an imaginary median line, and finely punctate ; 

 surface between the sulci smooth or subgranular. 



HoRNEBA STRIATA, M. Edwards, I. c, p. 21, pi. xi, fig. 1 ; Michelin, Icon. Zooph., p. 316, 

 pi. Ixxvi, fig. 7. 



Habitat. — C. Crag, S. Wood ; Doue, Michelin. 



11. H. RHOMBOIDALIS {fl. sp.) PI. XV, fig. 4. 



Ramis cylindricis, furcatis. Superficie anteriori reticulata, posteriori granulosa vel 

 rugosa, seriebus punctorum obliquis ornata. Cellularum orificiis orbicularibus, peristomate 

 paullulum incrassato marginatis, porumque supra gerentibus. 



Polyzoarium composed of cyhndrical, forked branches ; anterior surface strongly and 

 regularly reticulate ; mouths of cells orbicular, border annular, slightly thickened, a pore 

 above each ; dorsal finely granular or rugose, punctured in oblique rows. 



Habitat.— C. Crag, S. TFood. 



Genus 2. Idmonea, Lamouroux. 



Polyzoario raraoso ; ramis plerumque dichotomis liberis, vel subinde conjunctis ; postice 

 rotundatis, antice carinatis. Cellularum orificiis, in seriebus alternis, transversis vel 

 obliquis et in carina media angulatim conjunctis dispositis. 



Polyzoarium ramose, branches dichotomous or irregularly divided; free or anasto- 

 mosing ; mouths of cells disposed in parallel, transverse or oblique, usually alternate, rows, 

 on each side of the front of the branches, which is angular or carinate in the middle. 



Idmonea, Lamx., Exp. Meth., p. 80, 1821 ; Def ranee; Blainville ; M. Edwards; Johnston; 



Lonsdale ; Reuss ; Michelin ; Hugenow. 

 Idmonea (pars), Rtemer; D'Orhigny. 

 Retepoka (pars), XawzarcA;; Goldfuss ; Hagenow. 

 Reticulipora, crisina, stichopora, tubigera, saterocava, Semicellakia, lyOrhigny. 



1. Idmonea punctata, B'Orbig. {sp.) PI. XV, fig. 5 ; PI. XVI, fig. 3. 



Polyzoario ramoso seu fenestrato ; ramis subcylindricis ; cellularum orificiis parvis, 

 orbicularibus, prominulis, 3 — 4 singulis in seriebus. Superficie anteriori, posteriorique 

 punctata. 



