148 LOWER PENINSULA. 



into a large septal fovea. The septal fovea is, in its position, in- 

 dependent from the curvature of the polyp cells, but always repre- 

 sents the apertural fovea, whether it be in the median line of the 

 curved cells or in lateral position. Lamella3 about 120 in the cir- 

 cumference of calyces three or four centimeters wide, alternately 

 large and small. Near the calyx margin the plications have the 

 form of low rounded rugcE with granulose surface ; further inside 

 of the calyces the rugas transform into acute, stout, linear crests. 

 In vertical sections the superimposed bottoms of the incased cell 

 cups appear as large transverse diaphragms joining the outer walls 

 with deeply deflected margins. Occurs frequently in the upper 

 Helderberg limestones of Michigan, and in the neighboring States 

 to the east and west ; is also common in the drift boulders belong- 

 ing to the corniferous limestone formation. 



Plate LIII. — The upper row represents various silicified speci- 

 mens, partly found in the drift of Ann Arbor, partly from the corni- 

 ferous limestone of Port Colborne, C. W. 



ZAPHRENTIS NODULOSA, N. Sp. 



Curved elongato-conical polyparia of somewhat flexuose growth, 

 annulated by shallow constrictions and finer transverse wrinkles ; 

 vertically striate by septal furrows. The apiclcal portion of the 

 polyp cells is decorated by densely crowded, stout, spinulose projec- 

 tions, which gradually vanish on the upper parts of the cells. 

 Calyces deep, with erect margins ; bottom formed by a narrow, 

 almost smooth diaphragm deflected on one side into a large septal 

 fovea. The lamellae are sharp linear crests within the calyx ; near 

 the margins they become low rounded rugge ; about seventy in the 

 circumference of calyces one inch in diameter, alternately of larger 

 and smaller size. The sides of the lamellas are decorated by 

 irregular transverse rugae and granulations. 



Not uncommon in the drift of Michigan, in association with 

 corniferous limestone fossils ; also found in the corniferous strata 

 of Canada. 



Plate LV. — The right-hand side small specimen, in the lower 

 tier, represents a rather small calyx found in the drift of Ann 

 Arbor ; other larger specimens dilate more rapidly, and resemble 

 in mode of growth Zaphr. proliflca. 



