NATURAL SCIENCES OE PHILADELPHIA. 313 



raclials. Succeediug or free radials distinctly narrower than 

 those forming a part of the walls of the body, rounded on the 

 dorsal side, and, in the two posterior latei'al rays, all shorter than 

 wide, while the fifth one in eacli of these rays (other rays un- 

 known) is an axillary piece supporting two arms. 



First anal piece nearly as large as the subradial upon the upper 

 side of which it rests ; connecting on the left with the first radial 

 piece, and on the right with the first and second radials ; while it 

 supports others above, forming the base of the ventral extension, 

 which is composed of small pieces strengthened by radiating ribs. 



Arms of the two posterior rays rounded, composed of pieces 

 slightly wider than long, and each bifurcating at least twice (and 

 perhaps oftener) at unequal distances above their origin on the 

 last primary radial. 



Column of only moderate size for an inch or so below the base, 

 where it is very distinctly pentagonal, the angles being a little 

 rounded, with a rather deep furrow between on each side, com- 

 posed of short pieces, which near the base seem to alternate with 

 much thinner ones. 



Length of body, 0.28 inch ; breadth of same, 0.26 inch ; thickness 

 of column at its junction with the body, 0.09 inch; breadth of free 

 rays below the first bifurcation, O.OT inch. 



So far as the specimens afibrd the means of making a compa- 

 rison, this species would seem to be nearly related to Poteriocrinus 

 gr-acilis of Hall, described in the first vol. of Palaeontology of N". 

 Y., p. 84. His diagram and figure, however, do not show whether 

 that species has two of the primary radials of the right posterior 

 ray included as a part of the walls of the body, as in Denclro- 

 crinus, or whether it has more properly the structure of Homo- 

 crinus. He represents the first anal piece, however, proportionally 

 much smaller than it is in our crinoid, while, to the right, and 

 partly beneath the anal piece, he shows in his diagram a small 

 piece that seems to occupy the position and relations to other 

 parts of the subanal in true typical Poteriocr^nites} His speci- 



1 Prof. Hall also ranges it under Poteriocrinus in his corrected list of the 

 New York Fossils, published in 1859, after he had proposed the genera Ho- 

 mocrimis and Dendrocrinus, and included this form in the former group in 

 1852 ; from which we may infer that his type has more recently been found 

 to possess the structure of Poteriocrinites. In that case, it would of course 



1872.] 



