152 



PALJEONTOLOGY OF NEW-YOKK. 



543. 5. TREMATOPORA OSTIOLATA (71. j;?.)- 



Pl. XL A. Fig. 5o-ft. 



Coral irregularly branching ; branches numerous, cylindrical, gradually tapering towards the 

 extremities which are obtuse ; apertures of cells round-oval, distant from each other nearly 

 their diameter, arranged in spiral ascending lines or irregularly distributed over the surface j 

 intermediate spaces smooth ; stems solid, or incrusting other bodies ; internal structure showing 

 tubular or prismatic cells extending to the centre, with the interspaces transversely septate. 



This coral often commences growth by affixing itself to the stems of crinoids, and to other 

 corals ; but becoming thus attached, it throws out branches quite independently of any such 

 support. It is a very abundant species, and the branches are scattered profusely over the thin 

 calcareous layers in the Niagara shale, as well as in the shale itself. The apertures are some- 

 times unequally distributed, or the spaces between them unequal ; though the principal variety 

 of aspect arises from abrasion of the surface, which has obliterated the little elevated borders 

 around the apertures. The stems are sometimes slightly nodose, but for the most part smooth. 

 The species is easily recognized by its roundish-oval pores, which are generally evenly dis- 

 tributed over the surface, at about the distance of their diameter asunder. Where the branches 

 are hollow and flattened, it has the appearance of a Bryozoa, but the structure shown in the 

 solid stems and branches proves its distinction. 



Fig. 5 a. A specimen showing the coral surrounding the stem of a crinoid, and throwing out 



branches in several directions. 

 Fig. 5 b. A fragment of a bifurcating branch. 

 Fig. 5 c. An enlargement of the surface from the same specimen. 

 Fig. 5 d. A fragment slightly nodose, and having the apertures of the cells somewhat irregularly 



distributed over the surface, and the oval form rather more elongated than in the 



preceding figure. 

 Fig. 5 e. A portion of the surface of the same enlarged. 

 Fig. 5 /, g. Fragments showing the irregular mode of branching. 

 Fig. 5 h. An enlarged portion of fig. 5 g, where the elevated border of the aperture is more 



perfectly preserved. 

 Fig. 5 i. The end of a stem enlarged, showing arrangement of cells and interspaces. 

 Fig. 5 k. A portion of the last still further magnified, showing the structure of the intercellular 



spaces, and the empty or solid cells without visible septa. 

 Fig. 5 I. A longitudinal section of a hollow stem enlarged, showing the direction of cells. 

 Fig. 5 m, n. A small bifurcating stem, and an enlargement of the same, showing some sUght 



variation in the character of the apertures of the cell. 



Position and locality. In the Niagara shale at Lockport, Rochester and other localities. 



{State Collection) 



