250 PALEONTOLOGY OF NEW YORK. 



center of the aperture. Peristomes thin, distinctly and equally elevated, 

 not denticulated, sometimes finely granulose or with minute nodes. Cell 

 apertures regularly disposed in parallel longitudinal rows, from six to eight 

 rows on a branch, generally seven ; longitudinally the apertures are in con- 

 tact ; transversely they are separated by about half the diameter of an 

 aperture ; the apertures of the marginal rows are only a very little larger 

 than the others. The space between the rows of apertures is generally flat 

 or slightly concave, with a fine angular striation along the middle ; some- 

 times smooth, at other times the whole space is elevated and angulated ; 



when well preserved the surface is finely granulose. 



********* 



* 



Formation and locality. Hamilton group. West Williams, Province of Ontario, 

 Canada. 



Stictopora limata, n. sp. 



PLATE LXI, FIGS. 14-16. 



ZoARiOM consisting of a flattened, dichotomously branched frond, proceeding 

 from a spreading base attached to foreign bodies. Branches a little more 

 than 1.50 mm. in width ; margins parallel, the branches not widening before 

 bifurcation ; non-celluliferous marginal space extremely narrow, not wider 

 than .20 mm.; transverse section lenticular, angles at the margins very 

 acute, greatest thickness observed about .50 mm.; bifurcations compara- 

 tively distant, branches continuing for 15 mm. or more before bifurcating. 

 Cells tubular, parallel with the mesotheca for a portion of their length, then 

 abruptly curving and opening directly outward. The intercellular tissue 

 consists of irregularly disposed vesicles. Cell apertures oval, length about 

 .15 mm., width a little more than one-half of the length, disposed in longi- 

 tudinal parallel rows, separated longitudinally by the length of an aperture ; 

 transversely by twice the width of an aperture ; five rows on each face of 

 of the branch ; the apertures of the outer rows are larger than the others, 

 having a diameter of .25 mm., and are sometimes slightly oblique to the axis 

 of the branch. Peristomes thin, slightly and equally elevated ; there are 

 occasionally slight evidences of minute denticulations from the inner face of 



