REVISION OF PALEOZOIC STELLEROIDEA. 231 



Formation and locality. In the lower part of the Richmondian at 

 Moore's Hill, Indiana. It was found by C. B. Dyer, and is now in 

 the Museum of Comparative Zoology, Harvard University (No. 21). 



ALEPIDASTER FLEXUOSUS (Miller and Dyer). 

 Plate 36, fig. 4. 



Protaster flexuosus MILLER and DYER, Journ. Cincinnati Soc. Nat. Hist., vol. 1, 

 1878, p. 31, pi. 2, figs. 1, la. MILLER, N. Amer. Geol. Pal., 1889, p. 276, 

 fig. 409. PARKS, Trans. Canadian Inst., vol. 8, 1908, p. 368. 



Protasterina ("Protaster" lapsus) fimbriata ULRICH, Journ. Cincinnati Soc. Nat. 

 Hist., vol. 1, 1878, p. 95, pi. 4, figs. 9-9c. 



Protasterina flexuosa and P. fimbriata J. F. JAMES, Journ. Cincinnati Soc. Nat. 

 Hist., vol. 18, 1896, pp. 139, 140. 



Original description of P. flexuosus. " The disk is composed of very 

 thin, small plates, the order of arrangement of which is not deter- 

 mined. The specimens examined differ in size, and show the disk 

 varying in diameter from one-quarter to one-half an inch. The rays 

 were very flexuous when living, and are found winding and turning 

 and thrown in different directions in different specimens. 



"Four series of plates are seen upon the dorsal side of each ray 

 near the disk. The two inner series [the ambulacrals seen from the 

 dorsal side] form an angular ridge, each plate is concave at the uniting 

 surface, the arrangement is alternate, and the appearance, therefore, 

 of the top of the ray, is something like the alternate arrangement of 

 two series of hourglasses. The outer series, or marginal [side] plates, 

 are spinous, the spines directed toward the point of the ray. A 

 weathered ray shows three series of pores one row between the inner 

 series of plates, and one between the marginal plates and inner series, 

 upon each side of the ray [probably the plates are worn through by 

 weathering; there should be but two rows of podial openings, the 

 others being either muscle pits or weathering holes]. The plates are 

 a little the longest in the direction of the length of the ray, and in 

 this direction there are about four to the line. The rays cross the 

 disk on the dorsal side and unite near the center of it, but the speci- 

 men figured, Plate II, figure 1, has this part of the rays removed. 

 Plate II, figure la, illustrates the ventral side of a specimen, which 

 is too indistinct to show the arrangement of the plates. Small 

 pieces, showing the ventral side of the rays, from other specimens, 

 have two rows of spines springing from the marginal plates on each 

 side of the rays." 



Original description of P. fimbriata. 1 "Disk of medium size, circu- 

 lar. Dorsal side of disk, and rays to margin of disk, covered with a 

 granular integument. Ventral surface of disk provided with a large 

 number of outwardly directed, short and slender spines. Oral 



i Ulrich still maintains that this species is a good one and distinct from P. flexuosus. 



