The Column of Heterocrinus hetcrodadyhis. 3 



more, in leugtli. I have seen single pieces of it from six to nine inches 

 in length. The specimen from which the above measurements were 

 taken shows the beaded part of the column to be composed of forty 

 plates to the inch. It is in my collection, and shows five inches of the 

 column attached to the base. The plates in the beaded j^'^i't of the 

 column are thus seen to be three times as much in thickness as they 

 are within the first half inch from the base. 



3d. The third part of the column, commencing at the head, and 

 going down (though heretofore treated as representing the whole of 

 the column), is described by Prof. Meek (Ohio Paleontology, vol. i., 

 page 13), as follows : 



" Column, comparatively, rathei- large and strong, somewhat dis- 

 tinctly pentagonal near the body, with more or less rounded angles, 

 and composed of alternately thicker and thinner pieces ; the latter not 

 forming continuous discs, but consisting each of five minute sections, 

 disconnected from each other, and ranged as minute transverse nodes, 

 coincident with the five angles of the column, and with the minute 

 pieces at the connection of the latter with the body, that are described 

 above as sub-basals. Further down the column gradually becomes 

 nearly cylindrical, and the little intercalated pieces more and more 

 developed, until they coalesce and form complete discs, scarcely 

 distinguishable from the othei's." 



Only the pentagonal part of the column was known to Prof. Hall 

 when he described the species (Pal. of X. Y., vol. i., page 279). 



The base is cpiite small in proportion to the size of the column, and 

 frequently two or three, or even more, columns are found closely hud- 

 dled together in one base, attached to the column of a Glyptocrinus 

 decadadijlus, or to the column of a Heterocrinus simplex. It is rarely 

 ever found except attached to the cohunn (jf some other crinoid, and 

 from the frequency with which it is found in clusters, one upon the 

 other, or two or more in the same base, it would seem to have i^een a 

 parasite. It may not have been, however. 



The Heterocrinus heterodactylus is found at all elevations about 

 Cincinnati, from low water-mark to the top of the hills, though good 

 specimens are by no means common at any elevation. Taylor's creek, 

 back of Newport, Ky., a short distance beyond the first tollgate, and 

 limekiln hollow, at the head of Deercreek, have furnished a great many 

 heads, bases, and columns of this species. 



Ceraukus Pleukexaxtiiemus— (Green).— The pvgidium of a trilo- 

 bite, described in the Ohio Paleontology, on page Tdd, as Acidaspis 

 ceralepta (?) and figured on plate 14,' fig. 8, is undoubtedly the 

 pygidium of a Ceraurus pleurexanthemus. 



