?4 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



and supramarginal columns may be very distinct or may be ob- 

 scured as such. Accessory ossicles always more or less abundantly 

 developed. 

 Contains : 



Mesopalaeasterinae . 



Promopalaeasterinse. 



Anorthasterinse. 



]VEESOT»AL^:^STERIN.S:, new sulDfamily. 



Palseocomidae Gregory, Treat. ZooL, vol. 3, Echinoderma, 1900, p. 254. 

 Primitive Promopalseasteridse with the interbrachial areas small, 

 composed of one pair of inframarginals, single axillary interbra- 

 chials, and the adambulacral plates. 

 Contains : 



Mesopalseaster, new genus. 

 Spaniaster Schondorf . 

 Miomaster Schondorf. 

 Devonaster, new genus. 



MESOPALSEASTER, ne-w genus. 



Plates 7-11. 



Palseaster (part) of Authors. 



fArgaster Hall, Twentieth Rep. N. Y. Slate Cab. Nat. Hist., 1868, p. 287: rev. 



ed., 1868=1870, p. 329. 

 Mesopalseaster Schuchert, Fossilium Catalogus, Animalia, pt. 3, April, 1914, 



p. 24. 



J/<?so = middle, and Palseaster. Kot the largest of Palseasters of 

 authors. 



Generic clmracters. — Rays five, slender and tapering. Disk small, 

 with incipient interbrachial arcs. 



Abactmal area with distinct columns of radial and supramar- 

 ginal plates, between which are inserted rows of accessory pieces, 

 one or two on each side of the medial columns. In mature specimens 

 the radial columns are less prominent proximally than distally. 

 The accessory columns proximally may also have here and there 

 inserted on each side a smaller piece, when the area between the 

 supramarghials has not only three or five colunms of plates but also 

 other additional small plates. The inframarginal columns margia 

 the rays, while the supramarginals lie somewhat inside and above 

 the former. Between the two columns of marginals there may be 

 a row of accessory ambital plates. The arrangement of the plates 

 of the disk appears to be as follows: In the center there is a small 

 plate around which is a first ring of 7 pieces, followed by a sec- 

 ond ring ha\nng not less than 14 plates, and these are nearly of 

 one size. The medial ray columns terminate on the disk in 5 



