7 



onal plate, that abuts its superior sloping sides against the adja- 

 cent tertiary radials, that support the free arms. The six plates 

 that support the six free arms in this radial series abut against 

 each other without any intervening plates. 



There are, as shown above, twenty-two arms, in this species, 

 which are more than have been found in any species heretofore 

 described. If, however, the ray containing six arms and three in- 

 terradial plates is abnormal the species would have twenty arms 

 and still be so different from any species heretofore described that 

 no comparison with any of them would serve any purpose in dis- 

 tinguishing it. There is nothing to indicate that this six-armed 

 radial series may be abnormal and we believe it is in the normal 

 condition of the species. 



The first interradials are the larger plates of the calyx as ex- 

 posed on the surface, and larger, in fact, than any of the other 

 plates, unless the first primary radials, including that part which 

 forms the funnel in the columnar cavity should prove to have as 

 great or greater size. The one opposite the six-armed series or 

 first azygous interradial is the larger one and has eleven sides; an 

 approximate one is the smaller and has nine sides; the other three 

 have ten sides each. The first interradial is followed by a single 

 plate that extends nearly to the top of the calyx, and which, in 

 turn, is followed by one or two small plates that separate the arms 

 and connect with the plates of the vault, except in the azygous 

 area, where three plates separate the arms and connect with the 

 plates of the vault. The sutures between the plates in the upper 

 part of some of the interradial areas are not distinct in our speci- 

 men, and for that reason are not shown in the illustration. 



The dome or vault, as may be seen in the illustration, has part 

 of the plates broken away on the azygous side and some of the 

 sutures are anchylosed or obscure. It is, however, covered with 

 large, polygonal plates of very unequal size. It is most convex 

 toward the six-armed series opposite the azygous side and most 

 sinuate or depressed at the azygous interradius. No pores or pas- 

 sages through the vault between the arms have been found in our 

 specimen. 



The specimen from which the foregoing description is drawn is 

 the largest known Dolatocrinus. It was found in the Hamilton 

 Group, at the Falls of the Ohio, and is now in the collection of 

 Win. F. E. Gurley. 



