yZ SMITHSONIAN INSTITUTION 



PLATE XXXIII 

 (All figures natural size except where otherwise stated) 



PAGE 



Figs. 1-13. Ichthyocrinus laevis Conrad 277 



Fig. I. Conrad's type specimen much flattened; from his figure, Jour. Acad. Nat. Sci., Phil., 

 PI. XV, fig. 16. Specimen cannot be found. Lockport, New York. 



2. Original of Hall, Pal. N. Y., Vol. II, pi. 43, fig. 26 — a flattened specimen; right anterior 

 view. Am. Mus. Nat. Hist. Lockport, New York. 



},a. A very fine mature specimen, complete crown, with perfect contour below the arms ; 

 anterior view, showing pyriform calyx and BB but little visible beyond the column. 

 Am. Mus. Nat. Hist. Lockport, New York. 



3&. Oblique basal view, showing perfect rotundity of the specimen, and the IBB entirely 

 within ring of BB ; posterior interradius up. 



3c. Brachial plates at third axillary, showing a regular median radial ridge, and the imbrica- 

 tion of plates. 



3d. Enlarged cross-section of surface of brachials, showing the sharp imbrication of plates. 



40. Medium sized undistorted specimen, showing almost perfect contour of crown ; right 

 anterior view, showing pyriform calyx and BB visible at side. Author's collection. 



Lockport, New York. 



4&. Basal view of same, showing posterior rays to second division. 



50. Original of Hall's pi. 43, fig. 2c ; complete crown of young specimen, undistorted, antero- 

 lateral view. The second bifurcation of rays is about half way up. Am. Mus. Nat. 

 Hist. Lockport, New York. 



5&. Basal view, showing right posterior ray, with RA and base, together with parts of other 

 rays. 



6a. Younger specimen, also with perfect contour, posterior view. The second bifurcation 

 of rays is three-fourths to top of crown. Author's collection. Lockport, New York. 



6&. Basal view of calyx, showing right posterior ray. 



7. Very young specimen slightly compressed, lateral view ; showing second bifurcation of rays 



at very top of crown. Author's collection. Lockport, New York. 



8. Still younger, perfectly rotund, specimen with stem and crown complete; but one bifurca- 



tion of rays visible. Extreme juvenile stage of stem shown by great elongation of 



distal columnals, and absence of any intercalated ossicles. Author's collection. 



Lockport, New York, 

 go. Detached base to show the basal structures in detail ; exterior view with top columnal 



attached ; canal faintly pentangular. X 2. Author's collection. 



Lockport, New York. 

 96. Interior view of basal plates; showing triangular funnel shaped opening projecting from 



the inner floor of IBB and entirely concealing them. X 2. 

 9c. Same parts further enlarged, showing lobes of the axial canal passing down from the 



funnel interradially. X 3. See text-figure 10 for further detail, 

 ion. Complete crown with stem attached ; medium sized flattened specimen, right posterior 



radial view. Author's collection. Lockport, New York. 



10&. Outline of crown if undistorted. 



Iia. A larger flattened specimen from Lockport, anterior view. Author's collection. 

 116. Outline of crown as in its natural contour. 

 12a, h. A still larger specimen, with similar outline. Author's collection. 



Lockport, New York. 

 13a. The largest known specimen, laterally compressed ; right anterior interradial view, 



showing arms to sixth division. It has six bifurcations in some of the rays. Coll. Sir 



Edmund Walker, now in the University of Toronto. Grimsby, Ontario ; Canada. 

 136. Basal view of same; RA and greater part of BB included in column facet. 

 13c. Outline restoration of the specimen, to show its natural contour. 



Niagaran, Rochester shales; Silurian. Lockport, New York, and Grimsby, Ontario. 



