452 PALEONTOLOGY OF ILLINOIS. 



Wortheni is flat or broadly concave, instead of being moderately con- 

 vex with merely a central concavity. 



Locality and position Upper beds of Burlington Limestone, Burling- 

 ton, Iowa. No. 218 of Mr. WACHSMUTH'S collection. 



PLATYCKIKITES PLANTJS, O. and S. 



PI. 3, Fig. 5. 



Plah/cm'mig planus. OWEN and SHUMARD, 1852. Jour. Acad. Nat. Sci., Phila., new series, Vol. 2, p. 57. 

 Geol. Iowa, Wis. and Minn., p. 567, PI. 5 A, Fig. 4. 



(Burlington Limestone, Mr. WACHSMUTH'S collection.) 



PLATYCRINITES suBSPitfosus, Hall. 



PL 11, Fig. 2. 



Plalycvinvg ivltpinoivs, HALL, 1858. Geol. Iowa, Vol.1, Part II, p. 536. PI. 8. Fig. 9 and 10. 

 (Burlington Limestone, Burlington, Iowa.) 



PLATYCRJNITES BTJRLINGTOKENSIS, O. and S. 



PL 3, Fig. 6. 



Plalyerinvs urKng1(>nent,is, 18. C 0. OWEN and SHUMAHP. Jour. Acad. Nat. Sci., Pliila., 3d Ser., Vol. II. 



p. 60, pi. 7, fig. 5; Geol. Iowa, Wiscon. and Minn., (1852) p. 589, tab. 5 A, fig. 5 ; Shuinard. Cat. Pal. 



Foss. N. Am., part 1, Ech., (1865) p. 387 ; McChesney Trans. Chicago Acad. Sci., (1867) Vol. I, p. 4, 



pi. iv, fig. 3. 

 Platycrinvs inornatits, McCHF.sKEY, 1660. Kew Pal. Foss., p. fi; Illustrations same, (18C5) pi. 4, fig. 3. 



BODY under medium size, cup-shaped, gradually expand- 

 ing upward, not quite twice as wide as high, and composed 

 of moderately thick plates, with sutures (excepting those 

 between the basal plates) rather distinctly furrowed. Base 

 saucer-shaped, or between three and four times as wide as 

 high, rounding abruptly under, and moderately concave in 

 the middle below; facet for the attachment of the column 

 slightly impressed and very nearly circular. First radial 

 plates a. little wider than high, and but slightly broader 

 above than below, having a general quadrangular outline, 

 with the superior lateral angles truncated and incurved, and 

 the lower margins nearly straight or slightly convex in out- 

 line; sinus for the reception of the second radials about half 

 as wide as the upper part of the first, and not deeply exca- 



