48 



in any known species of the Palseocrinoidea. They did not be- 

 long to the economy of that order of animals. 



There are three secondary radials in each series, each one is 

 twice as wide as high, and, though hexagonal, and heptagonal, 

 and of the same general form, as the first radials, they are much 

 smaller. The upper concave faces of the third secondary radials 

 incline less, from the central apex, than they do in the axillary 

 plates of the primary radials. The tertiary radials vary in 

 number, from five to nine, in the different series, they are thin- 

 ner and proportionally wider than either of the lower series, and 

 being located, at the greatest circumference of the body, they 

 are arranged transversely, instead of being inclined to the right 

 and left, as in the primary and secondary series. The next 

 division takes place, in one-half of the rays, from the seventh to 

 the tenth plate, but no division is shown to take place, in our 

 specimen in the other half of the rays, notwithstanding one of 

 them is preserved as far as the sixteenth plate. In the higher- 

 rays, the plates are thin and transversely arranged, but the upper 

 face of each one is moderately concave, and, in the middle part, 

 slightly overlapped by a projection from the next succeeding 

 plate, as in the primary and secondary series. The transverse, 

 arcuate sutures are distinct and the slight overlapping does not 

 destroy the depression, but, on the contrary, it is correspond- 

 ingly depressed. There are, in the upper part, therefore, sixty 

 arms. 



The interradial areas are not of exactly the same shape, nor 

 are they filled with exactly the same number of plates, though 

 they have elongated, subovate, or lance-subovate outlines, 

 pointed above. There are from eighteen to twenty-five plates, 

 in each regular interradial area, but, on account of an injury 

 to our specimen, at the azygous interradius, the number of plates 

 in that area cannot be counted. The first regular interradial 

 plate rests between the upper sloping sides of the first primary 

 radials; in some areas it is followed by one plate, and in other 

 areas, two plates abut against it ; in one area, it is as large as 

 any of the succeeding plates, while in other areas, there are from 

 one to four larger plates above it ; in the widest part of one of 

 the areas, there are only two rows of plates, while in the others 

 there are three. The plates, however, become smaller toward 



