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768 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
supporting two arms from each division, or four to the ray. Arms divergent, 
long and rather slender; composed of moderately long cuneate pieces, which 
gradually interlock, and from about the eighth plate are strictly biserial. 
Anal plate narrower than the radials, its sides almost parallel. Form and 
position of the anus unknown. Column round and small. 
Horizon and Locality. — Upper and Lower Burlington limestone ; Burling- 
ton, Iowa. : 
The specimens figured are in the collection of Wachsmuth and Springer. 
Remarks. — Halls D. pocidlum, Bull. I. N. Y. State Museum, Plate 2.4, 
Figs. 16 and 17, is a large example of this species, and his figure 14 on 
the same plate is probably D. levis. 
Dichocrinus angustus Wuitz. 
Plate LX XVI. Fig. 11. 
1862. White; Proceed. Bost. Soc. Nat. Hist., p. 19. 
188]. W.and Sp.; Revision Paleocr., Part II., p. 83. 
A small and slender species. Calyx nearly twice as high as wide ; sub- 
ovoid; very little spreading above the basals, the upper end slightly con- 
tracting. Plates without ornamentation or convexity beyond their general 
curvature. Suture lines not grooved or indented. 
Basals forming a cup with rounded sides; the face for the attachment of 
the column not protuberant; it is circular and proportionally larger than in 
the preceding species. Radials almost twice as long as their width at the 
basi-radial suture ; facets wide, but shallow, and pointing upward. Costals 
two, forming a syzygy, each plate marked by two small nodes. Distichals 
three; the two lower, which form a second syzygy, together but little larger 
than the third, or axillary. Arms four to the ray, composed of a single row 
of slightly wedge-shaped plates. Pinnules long. Anal plate a little wider 
below than at the top. All other parts unknown. 
Florizon and Locality. — Upper Burlington limestone; near Burlington, 
Towa. 
Types in the Museum of Comparative Zodlogy. 
ftemarks.—'This species is so closely allied to D. devis Hall from the 
Lower Burlington limestone, that there is reason to doubt whether it is 
a good species; however, as a rule, the specimens from the upper bed are 
smaller, the arm plates less cuneate, and there are, so far as observed, always 
four arms to the-ray, which are invariably given off from the third distichal.. 
a 
