248 PALEONTOLOGY OF NEW YORK. 



Branches 2 mm. in width, diverging at an angle of forty-five degrees ; 

 margins essentially parallel; non-celliiliferous marginal space very narrow 

 or obsolete ; transverse section lenticular, greatest thickness observed a 

 little less than 1 mm. Cells tubular, arising very obliquely from the 

 mesotheca. Inter-cellular space occupied by irregularly disposed vesicles. 

 Cell apertures broadly oval, often nearly circular, length .25 mm., disposed 

 in sub-regular longitudinal lines, sometimes alternating and forming obliquely 

 transverse rows, six apertures in the space of 5 mm. measured longitudi- 

 nally ; apertures of the marginal rows slightly larger and more distant than 

 the others. Peristomes strong, posterior portion the more elevated. Aper- 

 tures separated by sinuous, interrupted longitudinal ridges, which are elevated 



equally with the peristomes. 



********* 



Formation and locality. Hamilton group, south of Auburn, shore of Cayuga 

 lake, N. Y. 



Stictopora ovata, n. sp. 



PLATE LXm, FIG. 24. 



ZoARiuM consisting of a flattened dichotomously branched frond, proceeding 

 from a spreading base ; branches about 3.50 mm. in width ; margins parcal- 

 lel, not expanding before bifurcating; non-celluliferous margin nari'ow, 

 width less than .40 mm. ; transverse section of the branch broadly lenticular 

 or somewhat acutely oval, greatest thickness about 1.30 mm.; bifurcations 

 comparatively distant, some of the branches continuing 25 mm. or more 

 without bifurcating; bifurcations diverging at an angle of from thirty to 

 forty-five degrees. Cells tubular, short, arising obliquely from the mesotheca, 

 curving and opening directly outward, gradually enlarging to the aperture. 

 Inter-cellular tissue consisting of irregularly di.sposed vesicles. Cell aper- 

 tures broadly ovate, the broader end toward the base of the frond, length 

 .35 mm., width three-fourths the length, regularly disposed in parallel 

 longitudinal rows, frequently alternating and forming oblique transverse rows; 

 longitudinally distant from .30 to .50 mm. ; transversely they are separated 



