IIUDSON-RIVEK GROUP. 



283 



Fig. 1 c. Section of the same. 



Fig. I d. Section and figure of a similar fragment of a column enclosed in a coral. 



Fig. 1 e. Fragment and section of a column where the discs are e.\cavated on their upper side, and 



have plain rounded edges with a penlapetalous impression on the e.xtremiiics. 

 Fig. 1 /. Fragment of similar character, having the upper edges of the plates fimbriated. 

 Fig. 1 g. Section of the same, enlarged. 



Fig. I h. A magnified portion of 1 f, showing the fimbriated edges of the discs. 

 Fig. 1 i. Separate plates or discs of a similar column, showing the variable character of lire marginal 



crenulations, one specimen being marked by si.x prominent angles. 

 Fig. 1 k. Two figures, showing the proportionate size of the larger and smaller discs in the columns, 



composed of plain alternating joints. 

 Fig. 1 Z. A fragment of slate, with impressions of various discs of columns. 



Fig. 1 m. Several of the same enlarged, showing their analogy with the preceding and following forms. 

 Fig. 1 n. Fragment of a column, with the edges of the discs rounded and slightly nodulose; iiitcr- 



mediate plates thin. 

 Fig. 1 0. Edges of the discs rounded and subnodulose; intermediate ones thin, nodulose. 

 Fig. 1 p. Edges of the dijcs rounded and smooth, the intermediate ones thin. 

 Fig. 1 r. Edges of the discs flat and broad, the intermediate ones thin. 

 Fig. 1 s. A fragment of slate with moniliform columns; the intermediate plates often being scarcely 



distinct, while in others they are half as thick as the larger ones. 

 Fig. I t. Large fragments of columns in the compact slaty rocks of the Hudson-river group, with the 



discs thick, the intermediate ones being scarcely visible. 

 Fig. 1 u. A similar fragment of a column, with a section of the end, showing its identity with the 



preceding figures. 



These figures illustrate nearly all the varieties of form usually seen in the columns 

 of this species. There are some others presenting deviations greater than those figured, of 

 which I have some doubt as to their specific identity, and therefore do not give them in 

 this place. I have also entertained some doubt as to the propriety of uniting the figures 

 from 1 n, pi. 78, onwards with the preceding, .since I have not been able to tiace a positive 

 connection between the remote forms, though fig. 1 e, which is clearly identical with the 

 preceding figures of columns, presents the pentapetalous impression on the extremity of 

 the discs. 



Position and locality. This one is the most common species of this family in the western 

 extension of the formation, occurring at Cincinnati (0.), Maysville (Kj'. ), and Madison 

 (Indiana). In numerous localities in New-York, fragments of the columns are abundant, 

 but I have never been able to find the body. Fragments of cohuuns, well preserved, are 

 abundant in western localities. Those figured are from Cincinnati (Ohio), Maysville 

 ( Kentucky) , Pulaski, Turin, Loraine, Boonville, and other places in New-York. 



(State Collection.) 



I am indebted to Mr. Joseph Clarke, to Mr. Anthony, and to Mr. Carly of Cincinnati, 

 for beautiful specimens of this species. 



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