134 



PALEONTOLOGY OF NEW-YORK. 



The preceding species approaclies in character the Poritis tuhulata of Lonsdale ; though 

 the cells are more closely arranged than in his figures, except in fig. 3 y. I have separated the 

 preceding species from this one, principally on account of the structure shown in the vertical 

 sections of the cells, which are also smaller and more closely arranged. The different aspects 

 produced by weathering do not offer reliable characters, since the same specimen often presents 

 a great variety of appearance. 



The following specimens arc found in a somewhat different condition from those of the 

 preceding plate. The cells also are for the most part larger, and the walls better preserved ; 

 sometimes standing out in relief, while the interstitial portions are worn away. The size of the 

 cells, although variable, is not more so than in the Catenipora ; and the difference of aspect is 

 often caused more by the greater distance between the cells, from the expansion of the inter- 

 cellular spaces, than by the increased size of the tubes. 



Fig. 1 a. A weathered vertical section of a hcmi^iihcric mass, showing the tubes partially in relief 



upon the surface, with the interspaces more abraded. 

 Fig. 1 b. An enlargement of several tubes, showing the stnicture of the interior. 

 Fig. 1 c. An enlargement from another part of the same specimen, where the cylindrical tubes 



stand out in relief. 

 Fig. 1 rf. A portion of the surface of the same specimen, showing the openings of the cells upon 



the surface, and the intercellular spaces. 

 Fig. 1 e. An enlargement from fig. ] d, showing the structure of the surface and the openings of 



the cells. 

 Fig. 1 /. The base of a weathered calcareous specimen, where the lamella; and septa are nearly 



all obliterated, showing the striated interior and exterior of the tubes. This specimen 



contrasts very strongly with fig. 2 a of the preceding plate. 

 Fig. 1 g. An enlargement of a portion of the preceding figure. 

 Fig. 1 A. A fraginent where the walls of the tubes are preserved, the elevated edges appearing 



to be produced by twelve points or granules, with here and there slight evidences of 



rays. 

 Fig. 1 i. The same enlarged, showing more distinctly the characters mentioned, and also the 



unequal distances of these tubes from each other ; in some cases the walls being 



nearlv or quite in contact, while in others they are widely separated. 

 Fig. 1 A:. A weathered surface, showing the exterior and interior surface of these cells. 

 Fig. 1 Z. A weathered surface of a specimen preserving the cylindrical tubes, where the in- 

 tercellular spaces have been filled with crystalline matter, which has assumed a 



minutely tubular or cylindrical form. Each little cylinder is rugose or crenulated, 



perhaps indicating the spaces between the transverse septa. 

 Fig. 1 m. Transverse section of the same, showing the ends of the minute tubes. 



Position (aid locality. This species is common at Lockport, in the lower part of the Niagara 

 limestone. It likewise occurs at Milwaukie, Wisconsin, in the same geological position (fig. 1 1). 



- (State Collection.) 



