CRINOID GENUS SCYPHOCRINUS 



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develop according to their tendencies, the roots, instead of spreading symmet- 

 rically as is usual with encrusting roots, assumed most irregular shapes; in 

 some, relatively long branches are grown all on one side (text-figs. 7, 8) ; in 

 others, lateral connection has produced a flat plate for a certain distance mostly 

 on one side, beyond the edge of which the branching roots become separate 

 again (text-fig. 9) ; in a case still further advanced, a flat plate has been 

 formed with a similar one-sided growth which has followed the course of the 

 recumbent stem for a considerable distance, the stem being as it were half 

 buried in the plate (text- fig. 10). In this specimen some of the root branches 

 are partly separated from the floor, as they are occasionally seen within the 

 collar in the regular bulbs. 



Figs. 7-10 



Roots of young specimens of Scyphocrinus attached to hard surface of mature bulbs, 

 developing unsymmetrically and chiefly toward one side : 7, 8, long branches, X 2 ; 9, flat 

 plate followed by small branches, X I; 10, flat plate with similar one-sided growth follow- 

 ing course of recumbent stem, X f. 



These remains are not at all common considering the number of bulbs in 

 the collection, and it seems probable from the rounded appearance of the stem 

 joint-face where detached that the young did not long survive their fixation 

 in so unfavorable an environment. 



MODE OF UNION BETWEEN PLATES IN SCYPHOCRINUS 



Examination of the material in hand has yielded some information as to 

 the union between the various plates. Superficially each suture appears as a 

 fine denticulate line, formed by the interlocking of closely spaced crenulae on 

 the apposed plate facets. In the calyx the facets usually consist of two or 

 more distinct areas for the insertion of ligaments. The first is a narrow, 

 usually continuous, often convoluted, band surrounding one or more depres- 

 sions, and forming the contact surface of the plate. The second area or areas 

 consist of the depressions or ligament fossae. The surface of each facet is 

 crenulated, the crenulae originating in the deepest portion of the ligament 

 fossae, radiating outward and crossing the contact band at right angles. The 



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