40 PALEONTOLOGY OF NEW YORK. 



Ptilodictya nebulosa, 



PI^ATK XVII, FIOS. 18-18. 



BtAaropora nebulosa. Hall. Twenty-sixth Rept. N. Y. State Mus. Nat. Hist., p. 99. 1874. 



Thirty-second Rept. N. V. State Mus. Nat. Hist., p. 102. 1879. 

 In part Jixchanypora (Ptilodictya) tenuis, Hall. Report of State Geologist for 1882. Expl. pi. 17, figs. 



7-13. 1883. 

 Suckanipora {Ptilodic: ya) ii^tUosa, Hall. Repoit of State Geologist for 1882. Expl. pi. 17, tigs. 14-16. 1883. 

 PaletcJtofa bifniiata. Hall. Twenty-sixth Rept. N. Y. State Mus. Nat. Hist., p. 107. 1874. 

 Bteharopora (/ Paiescfiara) bifoliata. Hall. Thirty-second Rept. N. Y. State Mus. Nat. Hist, p. 162. 1879. 

 PuUteharaf foliata {ill tiivm), llxLh. Report of State Geologist for 1882. Expl. pi. 17, tigs. 17, 18. 1883. 



ZoARiDM a thin foliate expansion, with a thickened, narrow, striated base, 

 Ironi which it abruptly expands. Cells tubular, arising obliquely from a 

 mesotheca ; arranged in subparallel longitudinal rows, rarely interrupted by 

 the intercalation of additional rows. Apertures oval or subquadrangular, a 

 little longer than wide ; length 30 mm. Cell walls coalescing and thickened 

 on the surface by silicification, forming prominent longitudinal ridges. Sur- 

 face marked by slightly elevated monticules, the centres of which are distant 

 from each other about 3 mm. ; on these the cells are larger than the others 

 and the cell walls thicker ; width of the largest specimen observed 70 mm. 



This species is readily distinguished from the others by its broadly spreading 

 form and the numerous slightly elevated monticules. 



The fossil described as Paleschara bifoliata in the Twenty-sixth Report of the 

 State Museum of Natural History has proved, on further examination, to be a 

 specimen of Ptilodictya nebulosa, in a crushed and distorted condition. 



Formation and localities. Lower Helderberg group, Catskill creek, and near 

 Clarksville, N. Y. 



RHINODICTYA, Ulrich. 1882. 



RhINODICTYA ? GRANULOSA, n. Sp. 



PLATE XVII, FIGS. 6,6; AMD PI.ATK XXIU A, FIGS. 18, 19. 



In part Etchanrpirra (Ptilodictya) lirata. Hall. Report of State Geologist for 1882. Expl. pl. 17, tigs. 



1-6. 1883. 



ZoAuiUM consisting of a bifurcating flattened stipe; bifurcations very infrequent. 

 Base obtu-sely pointed ; sides essentially parallel, width 1.50 mm. ; transverse 



