﻿WOOD] Xf.W AND OLD MIDDLE DEVONIC CRINOIDS 63 



Formation and locality. — Middle Traverse (Hamilton) or Alpena 

 limestone: Richard Collins' quarry, Alpena, Michigan. 



Cat. No. 26,397 (paratype), 26,398 (holotype and paratype), and 

 36,012 Rominger collection, l\ S. \. M. 



MEGISTOCRINUS ABNORMIS (Lyon) 

 ( Plate XV, 3) 

 [857. Lyon. Actinocrinus abnormis, Geol. Rep. Ky.. in, p. 479, pi. 4 figs. 



1, ia~b. 



The statement is made by Wachsmuth and Springer 3 that this 

 species is " devoid of ornamentation," and in the original description 

 of the species no mention is made of the character of the surface orna- 

 ment. An exceptionally well-preserved specimen of Megistocrinus 

 abnormis (Lvon) from the Hamilton of Louisville, Ky., retains the 

 surface ornament in a nearly perfect condition. This consists of hue 

 ridges radiating from the center to the sides of each plate (pi. xv. 

 fig. }). The center of the plate is slightly depressed, and the ridges 

 disappear in the region of the elevated and often truncated margin. 

 This ornament suggests that of M. depressus (Hall), hut differs in 

 the absence of minute tubercles at the center of the plates. The 

 ridges are also straighter and more regularly arranged. 



Formation and locality. — Hamilton : Beargrass quarry and else- 

 where about Louisville, Ky., Clark county, Ind., and Marion county. 

 Ky. 



Cat. Xo. 36,017 (Rominger collection), 42,429 (Ulrich collection ), 

 and 3>i4S U. S. X. M. Also in Massachusetts Institute of Tech- 

 nology, Xo. 1.222. 



MEGISTOCRINUS RUGOSUS Lyon and Casseday 

 1859. Lyon and Casseday, Amer. Jour. Sci. (2d ser.), xxvni, p. ->43- 



A well-preserved individual of this species differs from the type in 

 the structure of the anterior ray. In this the first interdistichal is a 

 comparatively large plate, and is moved downward until it rests upon 

 the truncated apex of the second costal. The first distichals are 

 consequently widely separated. The interdistichal is followed by two 

 plates, and these in turn by two minute interpalmars. The specimen 

 corresponds with the type in other respects. 



Wachsmuth and Springer 2 state in their description of .17. rugosus, 

 " Anal plate followed by rows of 4. 5. and 4 plates." etc. This 

 description may have been written of an abnormal individual, for in 



1 North American Crinoidea Camerata, p. 546. 



2 Ibid., p. 543- 



