194 PALAEONTOLOGY OF ILLINOIS. 



the first radials, extend to the sides — those crossing any one 

 side being all arranged parallel to each other, so as to form 

 with those on the adjacent plates, a series of concentric, equi- 

 lateral triangles. Sometimes these costae are, on the upper 

 plates, notched or more or less irregularly interrupted, while 

 on some of the upper interradial plates they shoAv a tendency 

 to become broken up into little, spine-like projections. Height 

 (on the anterior side) to the summit of the third radials, 1.89 

 inch; breadth at the top of the third radials, 1.65 inch; breadth 

 of base, 0.84 to 0.90 inch; height of do., 0.46 inch. 



The foregoing characters were given by us from a specimen from which the 

 summit and all the parts above the first secondary radial pieces, are broken 

 away. We had compared it carefully with a weathered specimen returned by 

 Prof Hall, with the name A. regalis attached, and as our specimen not only 

 presents some differences in the details of its sculpturing, but differs in having 

 three instead of two plates in its second range of anal pieces ; thus giving a 

 heptagonal instead of a hexagonal form to its first anal piece ; while it also has 



a greater number of pieces in 

 the third and fourth ranges 

 of the anal series, and has the 

 interradial spaces so drawn 

 inward? above as to apparent- 

 ly indicate that it had not the 

 summit dilated above, as in 

 A. regalis, we supposed it to 

 be distinct, and described it 

 under the name A. speciosus. 

 Since publishing our descrip- 

 tion, however, we have had, 

 through the kindness of Mr. 

 Charles Wachsmuth, of Bur- 

 lington, an opportunity to ex- 

 amine a fine specimen (see fig. 

 7, p. 192) agreeing almost ex- 

 actly in form, general appear- 

 ance, and the sculpturing of its 

 ah I * „ f frotocrinusregalis j t ith Qur cri id &nd 



About half natural size. Made out from the specimen r ' ' 



figured on plate 16, figure 6. y e fc stowing clearly that it 



has the dilated summit, and structure of the upper parts seen in A. regalis. 



