406 Mr. F. M'Coy on some new Mesozoic Radiata. 



external margin broad, central oval hollow, deep : long dia- 

 meter 6 lines. 



Among mesozoic crinoids the present genns is well character- 

 ized by its column, and as this is a large well-marked species, I 

 have not hesitated to characterize it from the portion known on 

 account of the interest attaching to its geological locality, the 

 genus being hitherto only found in the upper chalk. 



Rare in the Bradford clay at Bradford. 



(Col. University of Cambridge.) 



Apiocrinus exutus (M'Coy). 



Sp. Char. Cup ovate (less ventricose in the middle than the A, 

 Parkinsoni, Schlot., and more so than the A. elegans, Def.) ; 

 about six of the upper columnar joints widen to form the base 

 of the cup and increase greatly in thickness; on the upper 

 columnar joint rest five pentagonal pelvic plates, alternating 

 above which are five quadrangular basal radial plates (first 

 costals of Miller), on each of which the cuneiform axillary ra- 

 dial joint (scapula) rests, the intermediate plate being want- 

 ing ; on these rest two semiradial plates or arms ; diameter at 

 upper columnar joint 1 inch 6 lines ; width of radial plates 

 9 lines, depth of each in middle 3 lines, depth of pelvic plates 

 in the middle 4 lines, depth of upper columnar joint 4| lines ; 

 columnar articulation very finely radiated. 



The comparative slenderness of its form and thickness of the 

 upper columnar joints make it intermediate in those points 

 between the A. Parkinsoni (Schlot.) and A. elegans (Def.), while 

 it is distinguished from all of the genus by the want of the in- 

 termediary radial joints (or second costse) in each row. 



Rare in the Bradford clay, Bradford. 



(Col. University of Cambridge.) 



Pentacrinus dichotomus (M'Coy). 



Sp. Char. Column, auxiliary side-arms, pelvic and costal joints as 

 in the P. Britannicus (Schlot.), but the entire animal smaller 

 and more slender, and the auxiliary side-arms proportionally 

 wider ; each of the five scapulse supports two slender arms of 

 nine or ten joints each, the last joint cuneiform, and support- 

 ing two slender hands of equal thickness, the inner usually of 

 thirteen, and the outer of sixteen joints, each hand regularly 

 dichotomizing into a few very slender fingers of perfectly equal 

 thickness ; auxiliary side-arms very thin, but equalling the 

 arms in width. Length of body and fingers 1-J to 2 inches. 



