25 



seem to belong to the radial series, and hence there is doubt about 

 the area. The first plate is in line with the first primary radials 

 and of about the same size. It is followed in the second range 

 by three large plates, and these, in the third range, by three 

 smaller plates, and above these there are two still smaller plates 

 that belong to this area. 



This species is so different from any other that has been de- 

 scribed, in the part preserved, that no comparison with any of 

 them will throw any light upon it. 



Found in the Niagara Group at St. Paul, Indiana, and now in 

 the collection of Wm. F. E. Gurley. 



ERETMOCKINUS COMMENDABILIS, 11. sp. 



Plate II, Fig. 15, a specimen showing .pari of calyx, arms and 

 column, azygous area on the right 



Species large. Calyx twice as wide as high, depressed in the 

 interradial areas and somewhat lobed in the superior part, broadly 

 truncated below. Plates moderately convex and granular, sutures 

 distict and more or less beveled. Column large and composed of 

 thick plates that are beveled externally, and alternately project one 

 beveled edge beyond the other. Columnar canal large and nearly 

 round. Basals short, truncated below and expanded to a thin 

 edge, irregularly hexagonal, in outline, and having a width twice 

 the diameter of the column. First primary radials 'a little wider 

 than high, three hexagonal and two heptagonal. Second primary 

 radials short, more than twice as wide as high, quadrangular. 

 Third primary radials a little larger than Ihe second, pentagonal, 

 axillary, and support on each superior sloping side two secondary 

 radial-. The secondary radials are larger than the second and 

 third primrry radials, the second one is axillary and supports on 

 each superior sloping side two tertiary radials. This arrangement 

 gives to the species twenty arms. This is upon the assumption 

 that the arm opposite the azygous area is like the three that are 

 shown in the specimen, it being possible that it has only two 

 arms. There are three single short plates in the commencement 

 of each arm, these are followed by a double series of interlocking 

 plates that are deeper than wide but which gradually widen, until 

 at the distance of an inch and three-quarters from the calyx an 

 arm is three times as wide as deep. 



In the only regular area shown in our specimen there are two 

 plates, one quite large followed by another half its size. The 

 first azygous plate is in line with the first primary radials and of 

 —4 



