﻿WOOD] NEW AND OLD MIDDLE DEVONIC CRINOIDS 57 



a triangular column with three secondary canals instead of a four- 

 angled column and four peripheral canals. 



TRIPLEUROCRINUS LEVIS n. sp. 

 ( l'i viK XVI, -', 2a.) 



Description. — Body small, sides diverging at an angle of about 

 45°. Surface smooth. Infrabasals not observed, but their presence 

 may he inferred from the truncated lower edge of the basals. Basals 

 pentagonal. Only two of these plates are preserved on the single 

 specimen found. Radials one-third larger than the basals, four- 

 sided below, the upper portion of the plate curving inward and back- 

 ward on either side to form a deep food groove. The structure of 

 the anal area cannot be determined. Arm facets occupying two- 

 thirds the width of the radials, and directed obliquely upward. 

 Width of the arm plates about twice their thickness. 



Plates of the column vary in size, every second or third plate being 

 larger. The central canal is triangular in section, with three small 

 circular canals opposite its sides and connected with it by short trans- 

 verse canals (see pi. xvi, fig. 2a). 



Formation and locality. — Onondaga limestone : Le Roy, New 

 York. 



Cat. No. 35,146 (holotype) U. S. N. M. 



MEGISTOCRINUS Owen and Shumard 

 1852. Owen and Shumard. U. S. Geol. Rep't. Iowa, Wis., Minn., p. 594. 

 For abnormal calyx development see M. sphccralis. 



MEGISTOCRINUS TUBERATTJS n. sp. 



( Plate XV, 2, 20-c. Plate XVI, 3, 3a.) 



Description. — This is a large crinoid with thick plates. The gen- 

 eral form of the body is globular, with the base flattened to the middle 

 of the first costals. 



The center of each plate of the dorsal cup bears a large and ex- 

 tremely prominent node which may vary in shape from a broad 

 cushion, covering nearly the whole surface of the plate, to a blunt 

 wedge or a rounded knob. Some of the nodes, more particularly 

 those on the radials, show a tendency to divide, forming a bi- or tri- 

 tuberculate crest. All these variations in form may be seen on the 

 surface of a single individual. The entire surface of the dorsal cup 

 is covered by extremely delicate, discontinuous ridges which radiate 

 from the center of each plate, covering the nodes as well as the spaces 



