CRINOID GENUS SCYPHOCRINUS 



17 



young stem was in many cases not attached or imbedded, but remained project- 

 ing above the general level of the roots, where it underwent a process of 

 gradual suppression and disappearance, frequently leaving a scar which is to 



Figs. 1-2 

 1. Bulbous root (Camarocrinus) of Scyphocrinus. Generalized figure constructed from 

 sectioned and fractured specimens in the author's collection. Showing the relation of the 

 stem and its outgrowths, viz., the pavement, the bordering collar, the branching roots and 

 sacs suspended from them with openings upward, all formed by extension and multiplica- 

 tion of root branches. Perforations for nerve cords may be seen on the exposed faces 

 of plates. Nat. 2. Part of fractured collar belonging to a large bulb, used in constructing 

 fig. 1 ; the plates have separated along the sutures, showing perforations for nerve 

 cords. X f. 



be seen close to the stem upon some very mature specimens (see Hall's 

 fig- 5> pl- 36, 28th Rep. N. Y. St. Mus. Nat. Hist.). Concurrently with this 

 process the stem in the opposite direction gradually changed its position from 



Figs. 3-6 



Stem and roots of Scyphocrinus, merging in bulbs not shown. Showing stages in 

 reduction and disappearance of primary terminal root at a, from a projection of several 

 segments with stem partly recumbent (3), to a mere flat scar with stem erect (6). All X 2. 



recumbent to erect, the latter being often not attained until the projecting point 

 or cusp had disappeared. 



Text-figures 3, 4, 5, and 6 show some of the stages of fixation of the stem 

 and disappearance of the terminal point. 



