NICKLES AND BASSLER.] DIAGNOSES OF GENERA. 47 



zocKcia long oblique tubes, with an occasional diaphraoni; apertures 

 ovate, very oblique, acute anteriorly, posterior niaru-in somewhat 

 elevated; at the upper extremity of the aperture an accessory pore. 



Genotype and only known species: Ptllotrypa oblinuata Ulrich 

 Ordovician. 



Intrapora Hall. 



Zoarium ramose, from a spreading base, branches compressed divid- 

 ing dichotomously; zooecia tubular, at first parallel to the mesotheca 

 then bend abruptly outward; apertures oval, with peristome- inter- 

 spaces with minute angular pits, the openings of the numerous 

 ttibulated mesopores; the interspaces sometimes solid, the inesopores 

 having been closed by a deposit of horizontally laminated calcareous 

 tissue. 



Genotype: Intrapora puteolata Hall. Devonian, Mississippian 

 Three species. 



COSCINELLA Hall. 



Zoarium an explanate frond, of anastomosing branches, from -i 

 spreading base; zoojcia tubular, resting upon the mesotheca, with 

 rather long, direct vestibules; spaces between the vestibules and the 

 margins of the fenestrules occupied by numerous tabulated mesopores 

 opening upon the surface as minute angular pits; apertures circular' 

 irregularly disposed. ' 



Genotype: Coscitiella degantukirRfiW 'Ax^t\ Sxmi^son. Devonian. Two 

 species. 



T^NioDicTYA Ulrich. 



Zoarium ramose, rising from a basal expansion; branches rather 

 narrow, compressed; zooecia short, tubular, oblong, both hemisepta 

 present; orifices subcircular, at bottom of a sloping vestibular area- 

 interspaces ridgelike. ' 



Genotype: Tmnlodlctya ramidom Ulrich. Devonian. Mississippian 

 beven species. 1 1 - 



Stictopora Hall. 



Zoarium ramose; zoo^cial tubes long, without hemisepta; apertures 

 with distinct peristomes; interspaces wide, sometimes with raised 

 lines. 



Genotype: Stictopora dcijantida Hall. Ordovician. 



Heliotrypa Ulrich. 



Zoarium bifoliate; zoc^cia subtubular, thin-walled, and prostrate 

 upon the mesotheca, superior hemiseptum moderatelv developed- ves- 

 tibules with thick walls, traversed obliquely by radiallv arranged 

 minute tubuli; .spaces between vestibules of xariable width, occupied 



