the tertiary radiuls. The last plate mentioned is in ])art a 

 ])late belonging to the calyx, but its superior faces are higher 

 than the ambulacral furrous and unite with plates belonging to 

 the vault. The vault is unknown. 



This is a peculiar species that will, at once, be distinguish- 

 ed, by the spinous plates, nineteen arms, and numerous inter- 

 radial s. 



Found by C. S. Hodgson in the Burlington Group, in Adams 

 county, Illinois, and now in tht- collection of S. A. .Miller. 



UATOCKIXUS .SALKMKxNSIS. U. SJ). 



Plate I, Fig. 10, basal view; Fig. II, summH: Fig. 1l', tizygous side. 



Species small, vault and calyx subequal, di^pressed. bitur- 

 binate. Calyx saucer shaped, between two and three times as 

 wide as tiigh. Plates convex, radial series somewhat angular. 

 Ambulaci'al openings directed horizontally. 



Basal plates form an hexagonal disc one-half wider than the 

 diameter of the column and having a height equal to about 

 one fourth the diametei- of the column. The depression for the 

 attaclimcnt of the column is hcmisiiherical. The first i)rimary 

 radials are between two and throe times as wide as long, three 

 hexagonal, two heptagonal. Second primary radials quad- 

 rangular, short, from three to five times as wide as long. 

 Third primai'y radinls only a little larger lh;in the .second, 

 Ifoiii (hri'c 1(> loni- tiMK's as wide as long, ]ientagonal, axillary. 

 and, ill lour oL the rays, liear upon each uppei- slojjing side 

 two secondary radials the last ones of which are axillary and 

 bear u])on each u])])ei- sloping side two tertiary, which gives 

 to each of these rays four arms. In the ray opposite the 

 azygous area, the third primary radial bears upon each upper 

 sloping side three secondary radials, which gi\-es to it two 

 arms. There are, therefore, eighteen arms, in tiiis species, 

 and eighteen ambulacral openings to the vault. 



In each of two of the regular intorradial areas there are 

 three plates, one large followed by two small plates. In each 

 of the other two areas there are only two i)lates, one lai'ge 

 plate followed by one plate in the second range In the 

 azygous area there are six plates. The first one is in. line 



