NIAGARA GROUP. 



133 



Fig. 2 A. A portion of the vertical section in the same figure enlarged, showing the lamellae in 

 the interior of the cells with interrupted transverse septa ? 



Fig. 2 i. An enlarged figure of a vertical section, showing the transverse septa crossing the 

 cell directly and intcrruptedlj- ; also in other cells having the appearance of spini- 

 form ascending rays, as in fig. 2 e. The openings of the cells upon the surface of 

 this specimen are somewhat larger than in fig. 2 a, and show a gradation in size to 

 those of the figures on the next plate. 



Fig. 2 A:. A portion of the surface of a weathered specimen, presenting the principal varieties of 

 appearance assumed by this coral. 



Fig. 2 I, m, n. Enlargements showing the different aspects of the surface in fig. 2 k. 



Position and locality. In the lower part of the Niagara limestone at Lockport, New- York. 



521. 3. HELIOLITES PYRIFORMIS? 



PL. XXXVI A. Fig. \ a-m. 



Compare Porites pyriformis (Ehrexberg), Lonsdale : Murchison, Sil. System, pag. 686, 



pi. IG, fig. 2, 2 a - 2 e, 1839. 



SYNONYMES AND REFERENCES. 



Millipora siihrolundata. Fougt, 174.5. Lixne, Amoen. Acad. t. 1, p. 203, f. 24, 1749. 

 HdioUthe ptjri forme. Guettard, Mem t. 3, p. 454, pi. 22, fig. 13, 14, 1770. 

 Madreporites stellatus. Schlotheiji, Petref. p. 362, 1820. 

 Madreporites inter slindus. Wahleuberg, Nova Actae Upsalae, p. 98, 1821. 

 jistrea porosa. Goldfuss, Petrefacta, p. 64, I. xxi, fig. 7, 1826. 



— — HisiNGER, Lethea Succica, p. 98, tab. xxviii, tig. 2, 1837. 

 Astrea inlerstincta. Hisinger, Esquisse Petref. Sutde, 2rl Edition, p. 36, 1831. 

 Madrepora porites. Ehrexberg, Abhandl. Konig. Akad. Berlin, p. 344, 1832. 

 Heliopora pyriformis. De Blainville, Man. d'Aclinologie, p. 392, 1834. 



— — Steininger, INIem. Soc. Geol. France, t. 1. p. 346, 1834. 



—r — MiLXE Edw.ards, 2J Edition L.^jiarck, t. 2, p. 437 note, 1836. 



Heliopora interstructa. Bronn, Lelhea Geognostica, Vol.1, p. 48, tab. v, f. 4, 1835. 



Cells tubular ; rays short, transversely septate, septa more or less interrupted ; interstices with 

 tubular openings upon the surface ; vertical sections cellular or tubular. 



This coral scarcely differs from the preceding, except in the size of the tubular cells, which 

 are larger and often more widely separated from each other. The internal structure of the cells, 

 as shown in vertical sections, is usually transversely septate ; and the crowded spiniform rays 

 are not often visible, though the two kinds of structure have been seen in a single specimen. 



I am strongly inclined to believe that this coral is not identical with Jistrea porosa of Gold- 

 FDSS, if specimens from Gothland sent me under this name are authentic ; but it is perhaps 

 identical with a smaller species from the same locality, which has come to me without a name. 

 These two European species are evidently quite distinct from each other, presenting more 

 reliable characters for separation than tlie-ajiecies in the Niagara limestone. 



