FOSSILS OF THE m.M. MKASTRKS. 



Subgenus ZEACRixus. . 



ZEACKIXUS? MUCROSPIXUS, McC. 



PL 24, Fig. 12. 



Zracrinus mticroqmm.*. MC<L'HI->M-:Y. l^t. Xi-w. Pal. Fust*.. p. 10 : also Is6fi illustrations of same, pi. 4, 



tii:. 7. a, b. 

 Zeacrinu* .' muernqtinut, MEEK. l?7-i Final Report on Nebraska, p. 1-49, pi. 5, fig. 2, a. It. c. 



Position ami hcaUty Roof shales of Xo. 8 coal, Springfield, Illinois; 

 and various other localities in the upper Coal Measures of Illinois. 



ZEACRINUS (HYDREIOXOCRIXUS?) ACAXTHOPHORUS, 



M. and W. 



PI. -24, Fig. 11. 



niii ( Hyd reioneri nir* .' ) acanOiophoruz, MEEK and \TORTHKX, 1870. Proceed. Acad. Xat, ScL, 

 Pliila.. p. >. 



BODY below tin* top of the first radial pieces much de- 

 pressed, or nearly saucer-shaped, but concave below. Base 

 very small, and almost entirely hidden in the concavity of 

 the under side, when the column is attached.- Subradial 

 pieces small, four of them included in the concavity of the 

 under side, and projecting horizontally outward into rather 

 acute angles between the first radials, so as to present a 

 sub-trigonal general outline, though they are really hex- 

 agonal. their lateral and inner edges being connected with 

 each other and to the base, so as to form four very short 

 sides, with line, obscure angles; fifth one larger than the 

 others, proportionally longer, and curving upward at the 

 outer end, which is truncated, so as to form a short side 

 for the support of one of the anal pieces. First radial 

 pieces comparatively large, widening rapidly from below 

 to the to}. which is truncated evenly the entire breadth, 

 and about twice as wide as the greatest hight, all curving 

 under to connect with the subradials below in such a man- 

 ner that the body rests upon them when placed upon a 

 plane surface, with the column removed. Second radials a 



