INVERTEBRATES. 337 



Collected by A. H. Worthen from the Chester limestone in Monroe 

 and Pope counties. 

 No. 2,478, Illinois State collection. 



ARCEUEOCTDARIS EDGARENSIS, Sp. nov. 



PL XXX, Fig. 15. a. b. c. 



Primary spines long, gradually tapering, cylindrical; articulating 

 end perforated with a round aperture, and enlarged in a space of 

 about a quarter of an inch into a strongly striated ring, from which 

 it rapidly decreases above to its normal diameter at the articu- 

 lating extremity. The upper portion of the primary spines for about 

 three-fourths of their entire length are rather thickly set with short 

 lateral spinules, that project upwards towards the extremity of the 

 spine, where the latter terminates in a mucronate point. 



Interambulacral plates hexagonal, length and breadth nearly 

 equal, with a single row of granules on the rim of the smaller 

 plates, while on the larger ones two or more rows of small granules 

 may be seen. 



This species bears some resemblance to A. mucronatus, Meek and 

 Worthen, described and figured in Volume 2 of these reports, page 

 295, PI. 23, fig. 3, a. b. c. That species was obtained from the 

 Chester limestone, and the A. Edgarense may be readily distin- 

 guished from that by its shorter and more numerous spinules, its 

 strongly striated ring, and the less robust character of its primary 

 spines. 



Position and locality : Upper Coal Measures, one mile east of Bald- 

 winsville, Edgar county, 111. 



No. 2,447, Illinois State collection. 



ARCILEOCIDARIS SPINO-CLAVATUS, Sp. nov. 



PL XXX, fig. 14. a, I, c. (1, e, and Vol. 5, PI. XXIV, flg- 13. a, b, c, d, e 



Primary spines rather long, moderately stout, cylindrical at the 

 base and gradually increasing in diameter toward the upper ex- 

 tremity to twice or three times the diameter below, and then rapidly 

 diminishing to an obtuse termination. 



The enlarged upper portions of the spines are sometimes subtri- 

 angular in section and thickly covered with nodose spinules, which 

 are longest on the angles, and directed upward toward the apex of 



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