﻿WOOD] NEW AND (M.I) MIDDLE DEVONK CRINOIDS 59 



Remarks. — This species of Megistocrinus differs from those 

 already described in the presence of prominent nodes on all the plates 

 of the calyx, in the form of the nodes, and in the delicate surface 

 markings of the test. The specimen figured as the type of this species 

 (pi. \v. _', 2a) is incomplete, little more than half of the dorsal cup 

 being present, but it is not compressed, and shows the form of the 

 bod) and the surface markings extremel) well. The diagram of the 

 plates is from a more complete but badly distorted individual. ( >n 

 the surface of the latter specimen the delicate ridges have been en- 

 tirely effaced, and the height of the tubercles considerably reduced 

 by solution, but the suture lines between the plates are distinctly 

 visible and the number and arrangement of the arms clearly indi- 

 cated. The specimen from which the tegmen is drawn (pi. xv, 2c) 

 is the largest specimen studied, and though somewhat crushed, 

 measures approximately 45 mm. from the base to the posterior oral. 

 and 53 mm. in greatest diameter. The calyx of a young individual 

 is nearly complete. The full number of plates is present in the 

 dorsal cup, and the surface nodes are unusually prominent. A 

 slightly smaller specimen is abnormal in possessing but three arm 

 openings in each of the postero-lateral rays. The space between the 

 existing arm bases is, however, sufficient for two additional arms 

 and their absence may be due to an injury received during the life of 

 the crinoid. Figs. 3, 3a, pi. XVI, represent a very young specimen, 

 measuring 9 mm. in height, and 11.5 mm. in diameter. In this the 

 distichals are the highest plates of the dorsal cup, and the arm plates 

 rest directly upon them. The arms are sixteen in number and 

 arranged as in the adult. Tubercles on the surface are large and 

 prominent, occupying nearly the whole surface of each plate. Hates 

 of the tegmen are strongly convex, and three of the radial dome plates 

 bear short spines. 



Formation and locality. — Upper Traverse limestone : Partridge 

 Point, south of Alpena, Michigan. 



Cat. Xo. 26,395 (holotype and paratypes ) ; 36,015 Rominger col- 

 lection, U. S. X. M. 



MEGISTOCRINUS REGULARIS n. sp. 



(Plate XV, 4. 4a.) 



Description. — Dorsal cup low and broad; base flattened; sides 

 straight, forming an angle with the base of about 6o°. 



Entire surface of the basals elevated. Radials often Hat or even 

 depressed at the center. Other plates of the dorsal cup strongly 



