386 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



FIG. 571. Lateral view of the centrodorsal and infrabasals in a young pentacrinoid larva of Antedon 



mediterranea from Naples. (After Bury.) 



572. The radial circlet and inclosed structures of specimens of Uintacrinus socialis from Kansas ; 

 (a) a specimen with basals and infrabasals within the radial circlet; (6) a specimen with 

 basals only within the radial circlet; the small subpentagonal central plate in each figure 

 is the centrale, representing the central or suranal plate of the echinoids and the entire 

 column in the stalked crinoids. (After Springer.) 



PLATE 8. 



FIG. 573. -Lateral view of an immature specimen of Atelecrinus balanoides from Cuba, showing the 



proportionately large size of the basals in the young. (After P. H. Carpenter.) 

 574. -The centrodorsal and radials of a specimen of Atelecrinus balanoides. (After P. H. Carpenter.) 

 575. Dorsal view of the basals and radials of a specimen of Atelecrinus balanoides from the West 

 Indies. (After P. H. Carpenter.) 



PLATE 9. 



FIG. 576. Lateral view of the skeleton of a pentacrinoid larva of Antedon bifida from England, at the time 

 when the arms are just beginning to appear, before the development of the cirri, showing 

 the relationships of the basals, radials, orals, and radianal. (After W. B. Carpenter.) 



PLATE 10. 



FIG. 577. Dorsal view of the radial pentagon of a specimen of Antedon bifida from England, showing the 



rosette in position. (After W. B. Carpenter.) 



578. The rosette of a specimen of Antedon bifida in position, with portions of the radials; this is the 

 magnified central part of the preceding figure. (After W. B. Carpenter.) 



PLATE 11. 



FIG. 579. Ventral view of the skeleton of the calyx and arm bases of a fully grown pentacrinoid larva 

 of Antedon bifida just before the loss of the larval stem, showing the relationships of the 

 basals and radials; the centrodcrsal has been removed. (After W. B. Carpenter.) 



PLATE 12. 



FIG. 580. An isolated basal of a young specimen of Antedon bifida at the time of detachment from the 



larval column, seen from the outside of the calyx. (After W. B. Carpenter.) 

 581. An isolated basal of a young specimen of Antedon bifida at the time of detachment from the 



larval column, seen from the interior of the calyx. (After W. B. Carpenter.) 

 582. Dorsal view of a basal of Antedon bifida in process of conversion into a rosette, showing the 



partial resorption of the first formed lamella. (After W. B. Carpenter.) 

 583. Ventral view of the calyx of a young specimen of Antedon bifida, showing the basals altered 



by endogenous growth in preparation for the formation of the rosette. (After W. B. 



Carpenter.) 

 584. Dorsal view of a basal of Antedon bifida which has been nearly remodeled by accretion and 



resorption into the form requisite to constitute the rosette. (After W. B. Carpenter.) 

 585 Ventral view of a basal of Antedon bifida in process of conversion into a rosette which has been 



nearly modeled by resorption and accretion into the form requisite to constitute the rosette 



by union with those on either side. (After W. B. Carpenter.) 

 586. Ventral view of a basal of Antedon bifida which has been nearly remodeled by accretion and 



resorption into the form requisite to constitute the rosette. (After W. B. Carpenter.) 



