144 



ridges extending from the base to the ten arms, along the 

 five rajs. 



Found in the Moscow shale of Section .~,. two feet above 

 the base ( two specimens ). 



Note.— This species is the first of the genus noted above 

 the Silurian, as well as the first representative of the genus 

 in America; the other species being known from Gotland 

 and England. 



Gems PLATYCRINUS. Miller. 



[Ety. : Platys, flat ; krinon, lily. J 

 (Miller, Natural History of Crinoidea, p. I'-i, 1821.) 



Calyx composed of three unsymmetrical and frequently 

 anchylosed basals. succeeded by five large ra dials, laterally 

 united by close sutures, their upper margins crescent-shaped. 

 The costals are small and axillary, the single series being 

 often entirely hidden. The distichals commonly in two rows, 

 the upper axillary, and bearing the palmars. The first row 

 of interradials is on a level with the arm bases, and is in 

 part inter brachial, and in part interambulacral. The suc- 

 ceeding interradials are all interambulacral. Anal interra- 

 dius of numerous plates. Arms simple, dividing and becom- 

 ing biserial, i. e., composed of a double row of plates. Pro- 

 boscis often present. Stem elliptical and twisted, with a 

 minute axial canal. 



Platycrixus ekiensis. Hall. (Fig. 26.) I loth Rep't 

 X. Y. State Mus. Nat. Hist., p. 119, PI. I.) 



Distinguishing Characters. — Small cup-shaped 

 calyx; comparatively large column facet, bor- 

 dered by a thick rim; anchylosed basals : radi- 

 ;ils wider than high, witli prominent articulat- 

 fig. 26. piaty- ing surface above: first costal quadrangular ; 



• rin us c r i c a s is ' ° 



(after Hain. second costal axillary, pentagonal : sub-angular 



arm joints; strong pinnules ; granulose plates. 



Found "in the shales of the Hamilton group, near Ham- 

 burgh. Erie County. X. V." (Hall.) 



