NIAGARA GKOtrP. 



161 



This beautiful little coral, occurs in fragments of the size of those figured, and rarely 

 larger. It appears from the best preserved specimens that several stems originated from a 

 common base, bifurcating frequently and spreading on every side, forming a broad expanded 

 or flabellate frond. All the specimens observed present the striated surface to view, the other 

 side always adhering to the rock ; and it is only by detaching fragments, that the character of 

 the celluliferous face can be ascertained. 



Fig. 1 a. A part of a frond of this species, natural size. 



Fig. 1 i. A strong branch with numerous bifurcating branchlets, which are thickened at their 



extremities. This specimen is much stronger than the prevailing forms of this species, 



but it offers no other essential difference of character. 

 Fig. 1 c A portion of the striated surface enlarged. 

 Fig. 1 d. A similar enlargement of the celluliferous surface. 

 Fig. 1 e, f. Parts of figs. 1 c and 1 d still farther enlarged. 



Position mid locality. In the shale of the group at Lockport, and rarely in the lower part 

 of the limestone at the same place. (State CoUectian.) 



556. 6. RETEPORA ASPERATO-STRIATA. 



PL. XL C. Fig. la-h. 



Frond composed of a thick network formed by the anastomosing branches ; interstices oval, 

 somewhat unequal, the shortest diameter being usually equal to the width of the branches ; 

 outer face asperate or echinulate-striate ; inner face poriferous, with three, four or more rows 

 of oval or subangular cells arranged somewhat in oblique parallel lines, or in quincunx order ; 

 apertures of cells in perfect specimens probably with an elevated border or calicle. 



This species is somewhat variable in the size of the branches and interstices, but there is not 

 sufficient difference to constitute a distinct species. In the stronger growing individuals the in- 

 terstices are larger, and the diminution in size corresponds in both branches and interstices. 

 To the naked eye, and to an ordinary magnifier, the outer surface appears simply striate, but 

 a farther enlargement shows the strise to be echinulate or denticulate. The striae are less strong 

 and sharp than in the preceding species. The cells vary from round-oval to elongated and an- 

 gular forms, and are sometimes closely crowded ; while in other examples they are separated 

 from each other a distance equal to the narrowest diameter, and the apertures are more nearly 

 round. 



[ PaLjEontolosy — Vol. n.] 21 



