NIAGARA FALLS AND VICINITY I75 



monticules, and traversed by slender, rounded, bifurcating ridges, 

 which appear as shallow grooves when the surface is worn; aper- 

 tures nearly circular, occupying the summits of prominent papillae; 

 mesopores present, but closed at the surface; large median tubuli in 

 the middle layer or mcsothcca. 



Rhinopora tuberculosa Hall (Fig. yy) (1852. Pal. N. Y, 2:170, 

 pi. 40E, fig. 4a-c) 



Distinguishing characters. Lamellose or explanate palmate 

 fronds; asperate and tubercu- 

 lous surface; tubercles mostly "**•-- .. - ' ^ 

 destitute of cells at the sum- ''■"'''"- 7^, 

 mit; cells rising in pustules on 

 the surface and opening by 



roundish oval or tripetaloUS rig. 77 Rhmopora tubercolosa with enlargement 



apertures. 



Found in the Rochester shale at Lockport (Hall) and probably 



also at Niagara. 



Genus diamesopora Hall 



[Ety. : dui, through; /xiffo?, middle; -opo?, pore] 



(1852. Pal. N. Y. 2:158) 



Zoarium ramose, of hollow stems lined internally by an epitheca; 

 zooecia sim-ple, hexagonal, or rhomboidal, with an oval orifice in 



the anterior half, which, with 

 /^ "' ^ - -■- growth, forms a tubular vestibule; 

 ' aperture with peristomes equally 

 elevated or highest posteriorly; 

 : \ intervestibular spaces compact or 



\ /■ horizontally laminated. 



^^ Diamesopora dichotoma Hall 



S ^ (Fig. 78) (1852. Pal. N. Y. 



■^ 2:158, pi. 40B, fig. 3a-d) 



Distinguishing characters. Cy- 

 lindric, hollow, regularly bifurcat- 

 ing stems (a thin crust inclosing 

 inorganic matter); interior of hol- 



Fig. 78 Diamesopora dichotoma with enlarge- 



^^^^ low branches transversely striate; 



cells opening upward in regular ascending or spiral lines; promi- 

 nent nariform peristomes; stems usually flattened. 



Found in the Bryozoa beds of the Rochester shales at Niagara, 

 usually in a crushed condition. Also at Lockport (Hall). 



\ 



