DEVONIAN FOSSILS. 497 



Formation and locality: Three Forks limestone, near the divide 

 between Gallatin Valley and Panther Creek, Bighorn Pass, Gallatin 

 Range, bed 21 ; S. L. Penfield. East slope of Antler Peak, Gallatin Range; 

 A. C. Gill. South slope of Antler Peak, Gallatin Range; J. P. Iddings. 



PACHYPHYLLUM Edwards and Haime, 1850. 



Pachyphyllum sp. 



Corallnm attaining large size (the present specimen measures 150 mm. 

 in longest diameter and is fragmentary). Corallites small (9 to 10 mm. 

 in diameter), separated by mural zones of about 2.5 mm. Septa, 32 to 34 

 in number, and alternating in size. 



The specimen studied is a massive weather-worn fragment, which does 

 not show the external surface of the corallum, nor the nature of the calyces. 

 The rock has also suffered considerably from compression, for, though the 

 limestone is scarcely altered, the corallites are flattened and the lines of 

 the septa and spongy exothecal and dissepimental tissue often broken and 

 discontinuous. The corallites vary much in size, owing probably to 

 difference in age, but are more uniform where the corallum is crowded. 

 The average of mature cells is, perhaps, as above stated. That measure- 

 ment, however, relates to the septate portion only. The mural tissue is 

 very finely vesicular and is not penetrated by the septa, which are about 34 

 in number. They are strong, but have not the Acervularia-like expansion 

 so strongly developed as in P. devoniense. Longitudinal sections show alter- 

 nating stripes of finely vesicular mural tissue and the longitudinally banded 

 septate portion. This is occupied by dissepimental plates, but the presence 

 of complete tabulse has not been ascertained. 



While I am convinced that this species is as yet undescribed, and 

 although the characters established are sufficient to enable one to distinguish 

 it from any forms known and to recognize it again at the type or adjacent 

 localities, yet I have not felt justified in proposing for it a new name, since the 

 material is scarcely suitable for illustration; and it is not improbable that 

 from other stations, more or less remote, new types will subsequently be 

 described, which it will not be possible to separate from this, owing to the 

 imperfections of the latter. 



The only species which, so far as I am aware, have been referred to 

 -32 



