474 PAL-£)NT0LO9ICAL REPORT OF GEOLOGICAL SURVEY. 



nearly equal in size ; sub-quadrangular ; as broad as high. From 

 each of these the arm takes its origin. 



Anal piece. Lozenge shaped; small; .rising from the smallest angu- 

 lar depression in the basal pieces. 



Lobe pieces. These remarkable appendages are five in number; un- 

 equal iusize; thick, rounded, and club-like; twice as broad as thick at 

 the superior extremity, tapering downward, and ending in a broad fan- 

 like manner, at the inferior extremity. They are divided into three un- 

 equal parts, the union of the parts being marked by sutures; the up- 

 per part not unlike a seed vessel, (when first discovered by the coun- 

 try-people these parts were supposed to be petrified seeds, and were call- 

 ed "petrified coffee-nuts;") it is more than one-third the length of the 

 whole lobe piece; with the middle piece it makes two-thirds the length; 

 the lower part is irregularly serrated, and marked by the impression of 

 muscular attachments; it fits into and is attached to the inside of the 

 basal pieces. 



Arms. Our species has twenty arms, in sets of four, rising from the 

 second series of secondary radials; they are composed of a double se- 

 ries of joints, beautifully articulating with each other — the salient an- 

 gles of one set filling the re-entering angles of the adjoining set; the 

 arms are regularly tapering from their insertion to the end, where they 

 terminate in a point, rising about one-fourth their length above the 

 highest point of the lobe pieces; each set is separated into pairs by 

 the lobe pieces, which embrace them on either side. It is not certainly 

 known that the arms are provided with cillia. 



This remarkable crinoid is found in the lower intercalated calcareous 

 beds of the millstone grit of Crittenden county, associated with Pentre- 

 mites obesus, <$rc. The vertical range -of this species is somewhat great- 

 er than that of that fossil. It was very abundant; immense numbers of 

 the fragments of the lobed pieces are found, especially of that part form- 

 ing its upper extremity. It is evident that they were easily separated, 

 for amongst the multitude of fragments only one specimen has been 

 found sufficiently perfect to show the arrangement of the parts compos- 

 ing it; this is slightly flattened by pressure, and is so much weather- 

 ed that no surface markings can be discovered. By the fragments of 

 the lobe pieces the lower intercalated limestone of the millstone grit 

 may be identified. 



