FROM THE EAE-yEOZOIC ROCKS OF JNOfANA, KENTUCKY AND OHIO. 



449 



mediately beneath them. They arc pentagonal, hexagonal, and septagonal. All these 

 forms arc found in some one or more of them. Each of these support another radial of 

 the second series. These also vary in form and size: some of them are subqnadrangular, 

 others pentagonal or hexagonal. The rays again bifurcate on these pieces, each of which 

 supports two large pieces, some of which are very large. The rays are continued by two 

 large pieces which reach to the base of the free rays. 



The interradial fields arc five in number; they have a general resemblance one to the 

 other, with many special differences. No two of them are exactly alike. The pieces com- 

 posing them, like those of the rays, vary in size and form. The first piece of these fields 

 rests in the angular notch between the first radial pieces; these a*re octagonal; four of 

 them support two pieces, and one, the largest of them, supports three pieces of the next 

 series ; these again support two arranged irregularly, and are continued by a series of two 

 rows of small pieces. One of the interradial fields show six or eight pieces ; the last are 

 very small, long and narrow, probably connecting with the covering — at least reaching to 

 the arm-bases. 



Interbrachial fields. — Those seen on our specimen are formed of two or three pieces. 

 Some of them are formed of three pieces, one above the other; the inferior piece resting 

 upon the summit of one of the first radials of the second series, wedged between the adja- 

 cent branches of the ray; the upper piece has a square truncation upon the summit, and 

 appears to support one or more narrow pieces. One of these spaces shows this arrange- 

 ment of the pieces. 



Free rays. — The number of the free rays arc not absolutely made out. The division of 

 the rays, on the body of the calyx, indicate that each primary ray bears four rays, or 

 twenty rays in all. 



The summit, as shown by a fragment (evidently of this species) , is covered by very small 

 pieces, slightly convex; arranged irregularly; or, as on some portions of it, around a cen- 

 tral piece which supports a short, blunt spine. 



Column round; opening unknown. 



The surface-markings upon the pieces in our specimens are (pate fine or indistinct. 

 Under a strong lens, those pieces upon which the markings arc seen, are covered with fine 

 parallel stria), parallel with the length of the pieces. The pieces composing the rays are 

 deeply pitted near the centre of them by two very distinct pits; the other pieces with a 

 single one. This marking is so peculiar, that a single plate of this species is certainly 

 known and referred to it. The rays can be traced by the double row of pits which mark 

 the pieces composing them. 



Well-preserved specimens will, doubtless, show a beautifully-marked species. 



VOL. XIII.- 



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