EE\T[SION OF PALEOZOIC STELLEROIDEA. 81 



Abactiiial area unknown, but probably that of Mesopalxaster and 

 nearest to M. shafferi. 



Formation and locality. — The holotype was found by Faber in the 

 Maysville formation at Cmcinnati, Ohio, about 350 feet above the 

 Ohio lliver. Tlie type is in the University of Chicago Museum 

 (No. 9575). 



RemarJcs. — Tliis interesting species need be compared only with M. 

 shajferi. It differs m having the axillaries in the axils of the rays 

 and not inside the basal infra marginals as in the latter form. Then 

 in M. shajferi the inframargmals are actuial m position tlu'oughout, 

 while in M. intermedius they are more on the sides. Further, m the 

 new form the ambulacral furrows are well developed with large 

 ambulacralia, while in Af. sliafferi the furrows are narrow and the 

 ossicles rarely seen. 



MESOPAL^ASTER FINEI (Ulrich). 

 Plate 7, fig. 5; plate 9, fig. 5. 



Palxaster finei Ulrich, Joum. Cincinnati Soc. Nat. Hist., vol. 2, 1879, p. 19, pi. 

 7, figs. 15-156. 



Original description. — ''Small; rays five, of medium length, rather 

 broad, pointed and narrower where they are attached to the much 

 contracted body [probably due to distortion], than they are about 

 the center of then- length. 



"Dorsal side of rays composed of four [about seven, the supra- and 

 infra marginals, radials, and two intercalary columns] rows of pieces, 

 that are quite close [?] fittmg, as wide as long, from 12 to 14 m each 

 row, and ui crease in size inward to the disk, which is composed of 

 irregularly shaped and prominent pieces, some of which are smaller 

 and others larger than those composing the rays; tlie pieces m the 

 marginal rows [four columns infra- and supramarguials] are more 

 prominent than the two [there are three, radials and two intercalary] 

 rows between them, and have a small pit in the center, probably for 

 the articulation of a spme [all of the plates originally bore several 

 short slender spines]. Madreporiform body rather small, circular, 

 very promment, and marked by strong striae, which become more 

 numerous toward the margin by intercalation. 



"Marginal [inframarginal] pieces on the ventral surface, convex, 

 quite as long as wide, and numbering in different specimens on each 

 side from 11 to 12 [probably not more than 8 or 9]; the piece at the 

 junction of the rays is three times as large as any other of the series, 

 subcircular and very convex. [It appears that this large plate is an 

 axillary interbrachial since upon it proximally rest two basal plates 

 of the inframarginal series.] 



