12i THE CRINOIDEA CAMEEATA OF NORTH AMERICA. 



Eucladocrinus pleuroviminus White. 

 Plate LXXIII. Fig. 4, Plate LXXIV. Fig. 1. 



1S62. Plalycrhms pleurovimitms — White; Proceed. Bost. Soc. Nat. Hist., Vol. IV., p. 17. 



1878. Eucladoerimts pleurovimhms — W. and Sp.; Proceed. Acad. Nat. Sci. Pliila., p. 244;, and 1881, Re- 

 vision, Pait II., p. 77. 

 Syn. Platgcrinus discoideus Hall; 1858 (not Owen and Shum. 1852) ; Geol. Rep. Iowa, Vol. I., 

 Part II., p. 535, Plate 8, Figs. 8*, b. 



A very large specie.? ; the calyx sometimes reaching a width of 60 mm. 

 The form of the dorsal cup extremely variable, from discoid to low cup- 

 shaped, and from distinctly decangular in its dorsal aspect to almost circular; 

 its height in some of the specimens scarcely a third of the width, in others 

 equal to one half. Plates of the cup very heavy, and frequently highly orna- 

 mented over the whole surface, sometimes only around the margins; while in 

 some cases they are almost devoid of any surface markings whatever. In 

 most of the specimens, however, the surface is covered by irregular wrinkles 

 and rugose ridges parallel to the margins of the plates, and similar ridges pass 

 from the lower edge of the radial facets to the inferior angles of the radials, 

 and from the column to the upper angles of the basals. Other specimens 

 have a broad, roughened single ridge at some distance from the margins of 

 the plates, and deep grooves at either side of it ; but in all of them the 

 edges of the plates are distinctly beveled, and the basi-radial and interradial 

 suture lines channeled. Ventral disk as high as the dorsal cup, and some- 

 times a little higher, its outer margin rising almost vertically from the upper 

 edges of the radials ; the median portions depressed. The species has ten 

 ami trunks given off from the radials almost horizontally, those of the same 

 ray being in sutural contact to the top of the first palmars ; they are quite 

 heavy at the proximal end, but taper gradually upward, and curve gently 

 from above the palmars upwards and inwards, supporting from the side of 

 every second plate a simple arm. 



Base pentagonal, with a funnel-shaped depression occupying two thirds 

 the diameter of the plate, the margin convex and on a level with the beveled 

 lower end of the radials. The interbasal suture lines more or less deeply 

 grooved, the basi-radial and interradial ones at the bottom of a broad, shal- 

 low channel. Radials moderately spreading, the lower face wider than the 

 lateral ones, the upper end slightly inflected to meet the interambulacral 

 plates, and the angles broadly truncated for their reception ; the plates 



