35 



the second plate is hexagonal, larger than the first, rests upon the 

 truncated upper end of the largest subradial and between the first 

 radial and a summit plate on the left, and the first and third 

 azygons plates on the right and is truncated at the upper end for 

 the fourth plate. This alternate arrangement continues as far as 

 the proboscis is preserved in our specimen. 



This species is peculiar in its comparatively long, rough arms 

 and wide azygous area. It need not be compared with any other 

 described species, for P. legrandeiisis is as near to it as any other, 

 and in that species there are twenty much shorter arms and a 

 narrower and different azygous area. 



Foimd in the Kinderhook Group, at Le Grand, Iowa, and now 

 in the collection of Wm. F. E. Gurley. 



It was found by John McCabe, of Quarry, Iowa, in whose 

 honor we take pleasure in dedicating this beautiful crinoid. 



POTERIOCRINUS HAMMONDI, n. sp. 



Plate III, Fig. 7 , azygous view, mag/iifietl ttcu diuiihrters: Fig 

 S, .same, natural size. 



Species small, but bearing long slender arms, which, when closed 

 around the proboscis as in our specimen, make the body subcy- 

 lindrical. Calyx obconoidal; height and greater diameter nearly 

 equal; plates smooth. Column rather large at the calyx, but taper- 

 ing for a short distance, wdieu it becomes of ordinary size and 

 consists of thin, round plates. 



Basals of moderate size, in proportion to the calyx, with superior 

 angles acute. Subradials hexagonal, wider than high, the one be- 

 low the azygous area is much the wider, but so broadly truncated 

 On top as to give it little if any greater length. First radials 

 about as high as wide, evenly rounded, pentagonal, and truncated 

 the butire width above, where the sutures are distinct but not 

 gaping. A single, very long, contracted aud rouu'^ed brachial, 

 supports ujion the upjier sloping sides, in each radial series, the 

 free arms. The contraction of these remarkably long brachials 

 actually constricts the body immediately above the calyx. One of 

 the lateral brachials is shown in our specimen, aud it is a little 

 shorter than either one adjoining the azygous side of the probos- 

 cis, and we may presume the one opposite the azygous area is the 

 longer one, as that is the case in Potcriocrinus maccabei and in 

 some other species. There are only ten arms in this species; 



