The Calceocrinidm. 389 



discussing that point here, — so as to prevent a repetition when 

 that species comes to be described and considered. 



€AL.€EO€RI^IDiE Meek and Worthen. 

 (Revised by Ringueberg.) 



Calyx and arms drooping, being bent into an inverted position, and 

 hanging downward alongside or against the column ; parallel with it 

 or diverging at a slight angle from it. Posterior side proximal to the 

 column. Column round, straight, or slightly curved towards the calyx 

 at its upper end, which is attached to the posterior side of the calyx. 



Arms three or more, always one anterior and two lateral, and in some 

 they are present on the posterior side. Ventral tube large. 



Calyx flattened anteriorly with a truncate base ; lateral sides parallel 

 or nearly so, anterior and posterior sides divergent from the truncate 

 base. Posterior side more or less rounded. 



Basal plates consolidated into a semicircular or subtriangular piece, 

 which is placed entirely upon the posterior side of the calyx and has its 

 straight side, which is nearly or quite as wide as the base of the calyx, 

 articulating with the truncate base-line of the anterior side by means of 

 a hinge-like joint, while its posterior rounded or truncate pyramidal 

 side fits loosely into an arch, having a similar outline, on that side of 

 the calyx. 



The basal piece is somewhat scoop-shaped, having the column inserted 

 at or near the posterior rounded margin, and directed more or less out- 

 ward from it, forming the handle of the scoop ; — the posterior margin, 

 which is incurved, representing the back, and the straight anterior mar- 

 gin the edge. 



The anterior margin of this piece, and the adjoining radial articulate 

 margin, are both furnished with grooves extending along the entire 

 margin, or have external semicircular depressions which extend half- 

 way through the plates from the outer side of the margin. These de- 

 pressions, when present, are most prominent on the anterior or radial 

 side of the articulation, and may be absent on the posterior or basal 

 side, their place being taken by slight sinuosities of the outer non-artic- 

 ular side of the margin. 



The grooves and depressions are for the reception of elastic ligaments 

 uniting the two sides. 



Externally this articulation has the appearance of a gaping joint or 

 fissure, closed by means of a flexible integument, but internally is 

 actually closed by the exact approximation of the inner edges of the 

 ligament-bearing grooves, and over which the ligaments pass. 



The posterior or curved margin was not attached directly to the arch 

 into which it fits, but was united by means of some elastic and flexible 

 medium, which allowed a considerable degree of separation at this point. 



