274 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



such ovarian pores piercing the plates of the disk, as described and 

 illustrated in O.flexilis, have been discovered." 



Formation and locality. In the Keokuk formation, at Boonville, 

 Missouri. The cotypes are said to be in the Miller collection. 



ONYCHASTER DEMISSUS Miller. 



Ony chaster demissus MILLER, Seventeenth Rep. Geol. Surv. Indiana, 1892, p. 685, 

 pi. 12, figs. 8-10; advance extras, 1891, p. 75, pi. 12, figs. 8-10; N. Amer. 

 Geol. Pal., App. 1, 1892, p. 680, fig. 1241. 



Original description. "This species hangs its arms down and folds 

 them like the claws of a bird grasping some small object, and in these 

 respects is more like 0. flexilis than either of the preceding species. 

 The central disk is slightly concave, subpentagonal in outline, and 

 the rays drop down at right angles to the circumference of the disk. 



"In the center of the disk there is a low, subcircular elevation, in 

 which I have been unable to find any sutures, or to determine whether 

 or not there is an opening of any kind ; it appears to consist of a single 

 plate. It is surrounded by a series of ten plates that form the sub- 

 pentagonal rim of the central disk. These plates are large, very 

 convex, radiately sculptured, and bent down in the direction of the 

 radial series as well as curving in to unite with the central plate. The 

 sculpturing is due to the sockets for the insertion of the rays. The 

 radial series commence from this circle of plates. The rays are 

 angular on the dorsal side or obtusely rounded. The dorsal side of 

 each ray consists of three series of plates, and there is one series on 

 each side, or five series in an arm. The first two plates in each ray 

 are connected laterally by smaller ones, which form part of the disk, 

 in the angular depressions, between the commencement of the rays. 

 All of the radial plates are more or less sculptured or pitted by the 

 depressions for the insertion of the spines. 



"The arms are longer, more angular, and have rather smaller spines 

 than either of the preceding species. I have been unable to detect 

 any ovarian pores, but spine sockets very much resembling pores are 

 indicated in figure 8, but they occur in the sutures and are readily 

 distinguished from pores that pierce the plates." 



Formation and locality. In the Keokuk formation, at Boonville, 

 Missouri. The three cotypes are said to be in the Miller collection. 

 There are two good specimens (No. 10994) in the Gurley collection at 

 the University of Chicago, and another specimen, from Crawfords- 

 ville, Indiana, in Yale University. 



FORMS WHOSE RELATIONSHIPS ARE UNKNOWN. 



CRIBELLITES CARBONARIUS Tate. 



Cribellites carbonarius TATE, Rept. Brit. Assoc. Adv. Sci., for 1863, 1864, Notices 

 and abstracts, p. 88. 



Original description. "This Asteroid, the first recorded from the 

 Mountain Limestone, is an impression of the upper surface, in a 



