FROM THE PALEOZOIC ROCKS OF INDIANA, KENTUCKY AND OHIO. 



4G1 



hydraulic limestone is thinnest, being about twenty feet. Several specimens, Hahytes 

 escaroides, have been obtained within eight feet of the base of the slate. 



Note. — It is with some hesitation that 1'. Leai is referred to Platyerinus. Our description will 

 show that it possesses characteristics that ought to exclude it from Platyerinus. It also differs from 

 Hexacrinus, Austin, and probably possesses characters of at least sub-generic value, by which it may 

 bo separated from other Platoerinoid forms. 



Note.— Since the above description was written, Dr. Knapp, of Louisville, Kentucky, has kindly 

 furnished me with several examples of P. Leal. They vary in size; some of thorn are shorter, others 

 longer than those figured. One of the specimens retains the epidermis upon two of the large radials, 

 and one of the basal pieces. The surface-markings on these consist of a finely granulose surface, 

 invisible to the unaided eye; upon this granulose surface are lines of larger granules, about one- 

 twentieth of an inch apart. The lines are not regular; they appear to start at the baso of the 

 lar"-o radials; converging, meet at the centre of the radials; those starting from the corners of the 

 pieces meeting at the arm-bases; those above, on cither side, parallel to the longest line below them. 



Genus DOLATOCMNUS. Lyon, 1857. 



Ky. Geol. Reports, Vol. III. 



DOLATOCRINUS MaRSIII, n. S. 



PL XXVII, Figs, n, n 1, n 2. 



Body, below the arms, discoid, with five broad, sharp carina, which rise perpendicularly 

 from the margin of the basal pit, and extend outward, equally elevated to the centre of 

 the third radials, the carina rising gradually from the margins of the radials, then more 

 rapidly to the centre of the pieces. At the centre of the third radials the carina sends 

 out branches, not quite so bold as the main stem, but strong, involving all the pieces of 

 the superradials up to the arm-bases. Arm-bases prominent, in groups of two to each 

 ray, producing a lobed, pentagonal figure of that section of the body. The dome is sub- 

 conical ; twice as high as the body below the arms ; surmounted by a thick, strong, sub- 

 central proboscis. The intcrradial fields unite to the dome-covering between the arms. 

 Basal pieces long; bending squarely (at right angles) into the basal pit; six-sided; the 

 upper part (not concealed in the pit) horizontally disposed. Second radial pieces sub- 

 quadrangular ; differing slightly in size. Third radial pieces pentangular ; varying in form 

 and size. The first, second, and third radial pieces of the several rays, differ very little in 

 length, in the same ray — the rays are of variable length. The third radials each support 

 two superradials, nearly as large as the ray-pieces below them. These support, some one, 

 others two superradial pieces beneath the arm-bases. Basal pit: this is filled by the 

 "atlas" of a column, such as that described in this paper. Its depth is not seen. Two 



