NicKLEs AND BASSLEK.l DIAGNOSES OF GENERA. 53 



Family CYCLOPORIDiE. 

 Cyclopora Prout. 



Zoarium nnilaminar, parasitic or free; zooecia su})tubiilar, hemisepta 

 wanting- or hut little developed; vestibules with rather thick walls; 

 between the vestibules arc mesopores crossed by thick diaphragms, 

 which usually have a central perforation and are open at the surface; 

 apcn-tures subcircular, with a smooth or granulose peristome; acan- 

 thopores sometimes present. 



Genotype: Cyclopora fungia Prout. Mississippian. Two species. 



Cycloporella Ulrich. 



Zoarium a thin discoidal expansion; zooecia subtubular; vestibuies 

 with a succession of superior hemisepta; irregular mesopores abun- 

 dant; numerous acanthopores of large size. 



Genotype: Cycloporella spinifera Ulrich. Mississippian. Two 

 species. 



Proutella Ulrich. 



Zoarium discoid, thin, free, under surface with a concentrically 

 wrinkled epitheca; zooecia subtubular, thin-walled; apertures broad- 

 elliptical, surrounded by a narrow sloping area, hexagonal in outline; 

 when perfect the apertures have a depressed calcareous plate that 

 closes a little less than two- thirds of the opening, the orifice left being 

 subtriangular in form, without thickened margins, and situated at the 

 anterior side: with age the vestibules become elongated and are inter- 

 sected 1)T incomplete diaphragms. 



Genotype and only known species: Cyclop)ora discoideaVYOut. Mis- 

 sissippian. 



Worthenopora Ulrich. 



Zoarium bifoliate, branching or palmate; zooecia very regularly 

 arranged, elongate rhomboidal; apertures semielliptical, the truncated 

 posterior margin somewhat raised; on the surface the line of junction 

 between adjoining zooecia is marked b}- an elevated ridge; the elongate 

 triangular space below the apertures perfectly plain. 



Genotype: Woi'thenojJorahij^inosaXJXvich. Mississippian. Two species. 



Family RHINOPORID^ Ulrich. 



Zoarium variable in form; zooecia prone along the basal membrane, 

 simple, oblong, or rhomboidal; vestibules direct, hemisepta wanting 

 or almost so; front of zooecia below vestibule commonl}' strengthened 

 with solid or vesicular tissue. 



