54 MESOZOIC RADIATA. 



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. Par-kinsoni (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. 



{Ool. 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 scapulae supports two slender arms of 

 nine or ten joints each, the last joint cuneiform, and sui)port- 

 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 li to 2 inches. 



This delicate little species has a very singular aspect, and dif- 

 fers from its congeners in the hands not continuing as thick main 

 branches, giving off comparatively thin fingers from one side, 

 but both hands and fingers dichotomizing into perfectly equal 

 branches. 



I have examined portions of eight heads, some nearly perfect, 

 with their columns and side-arms, on a slab of lias shale from 

 Whitby. 



[Col. University of Cambridge.) 



Pentacrinus Goldfussi (M'Coy). 



Sp. Char. Column pentagonal, joints alternately thicker and 

 thinner, or three thin between each pair of thicker joints, ar- 

 ticulating by five oval, prominent, finely crenated ridges, the 

 intervening spaces much depressed; auxiliary side-arms large, 

 flattened, of elliptical joints, five arising from every thick co- 

 lumnar joint (one from each side), the long axis being attached 

 vertically ; pelvic joints large, cuneiform ; first costals hepta- 

 gonal, twice as wide as long, flattened (not produced into a 



