- 172 PALEONTOLOGY OF ILLINOIS. 



Interradials ten to twelve to each area; the first one as large 

 as the third radials, or larger, the upper ones, which form a 

 shallow impression along the calyx, much smaller. There are 

 two plates in the second range, three in the third, and generally 

 two or three smaller pieces above. Interaxillaries three, small. 

 Azygous interradius much wider, consisting of three large plates 

 in the second range, three or four in the third, with several rows 

 above. The exact position of the anus is not known, but it evi- 

 dently was not placed laterally, as it cannot be seen between the 

 arm bases. Nothing is known of the construction of the vault. 



Column and axial canal small for this genus. The joints near 

 the basals are all large, while further down long and short joints 

 alternate. 



Geological position, etc. Same as the last species. 



Our own collection. 



GENUS BATOCRINUS Casseday. 

 BATOCRINUS MAC-BRIDEI (nov. sp.) W. & Sp. 



PL XV, Fig. 4. Specimen with arms, column and cirrhi. 



PL XVII, Fig. 12. Anterior side of another specimen. 



PL XVII, Fig. 11. A side view of the calyx, from its anterior side. 



This is the earliest and smallest known species of Batocrinus, 

 but it possesses all the characteristics of the genus. Height of 

 calyx and arms rarely more than an inch. The plates are but 

 slightly convex, and without ornamentation. Dorsal cup sub- 

 turbinate, broadly truncate at the base, with straight sides to 

 the arm bases. The vault is somewhat lobed, with a con- 

 spicuous depression toward the arm bases. The specimens have 

 a brownish color, much lighter, however, than those of Dicho- 

 crinus inornatus and Rhodocrinus kirbyi. 



Basals forming a shallow cup, truncated at the lower end, and 

 excavated for the reception of the column. The plates are 

 rounded upon the surface; deeply beveled at theinterbasal sutures, 

 forming notches, two of which are occupied by radials, the third 

 by the first anal plate. The upper margins are excavated to re- 

 ceive the lower convex sides of the three other radials. 



First primary radials one and a half times as wide as high, the 

 second short, quadrangular, more than twice as wide as high; the 

 third pentangular, not higher than the second but wider. Sec- 



