CONTRIBUTIONS TO PALiEONTOLOGY. 117 



The specimen is essentially entire : the column is attached by a spread- 

 ing root to the column of another crinoid. The column of the Chkirocrinus 

 is about two and a half inches in length; while the length of the body 

 and arms, when fully extended, has been about the same. From the posi- 

 tion of the animal and the direction of its column, it appears to have been 

 attached to the crinoid column while that body remained in a vertical 

 position, or while the animal to which it belonged was in a living state. 

 This seems the more probabh?, since, had it been attached to a fragment 

 lying on the bottom, the pendant arms of the Cheirocrinus would have 

 reached nearly or quite to the muddy sediment. 



Geological formation and locality. In the shales of the Hamilton group: 

 Ontario county. 



GENUS ANCYROCRINIIS ( n. g.), Hall. 

 In the shales oJT the Hamilton group, and in the limestone of the 



Upper Helderberg group, there occur numerous crinoidal bodies. 

 which, at one extremity, have the form of a bulb or thickened co 

 lumn, with lateral ascending processes and a central ascending 

 column of greater or less length. 



Specimens of this character, in what appear to be incipient stages 

 of growth, are like fragments of crinoidal columns, rounded anti 

 sometimes attenuated below, with a small articulating scar at the 

 extremity : recognizing this as the base, there proceed from the 

 sides obliquely ascending spine-like processes, of the character of a 

 crinoidal column, but tapering to an obtuse point, or sometimes 

 truncate. The central portion continues above these divisions, and 

 is marked by the transverse joints, while the part below and the 

 lateral processes are rarely thus marked. 



As the development progresses, this lower portion, and the part 

 around and above the lateral processes, becomes enlarged and swol- 

 len in the form of a bulb. The central column above sometimes 

 continues till the bulb acquires a comparatively large size; but 

 often it separates, and the cicatrix becomes more or less obliterated 

 and covered by calcareous accretion which sometimes assumes a 

 concentric lamellose structure. 



In the more perfect specimens the form is somewhat biturbinate, 

 the base rounded and larger than the portion above the processes. 

 In some of the forms the lateral processes are all nearly or quite in 

 the same range, while in others they are unequal, and often one of 

 them is considerably above the others at its origin. 



No structure has been determined in these parts; and thus far 

 we do not know the body, which we infer has been attached to the 



