MONOGRAPH OF THE EXISTING CEINOIDS. 385 



Fig. 552.— Lateral view of a radial from a specimen of Thaumatocrinus renovalits. (After P. II. 



Carpenter.) 

 553.— The proximal columnals, calyx and arm bases of a peutacrinoid larva of AnUdon bifida at the 



time of the development of the cirri. (jVftcr W. B. Carpenter.) 

 554.— Inner end of a radial from a specimen of Antedon bifida. (After P. BE. Carpenter.) 

 555.— Dorsal \'iew of a radial from a specimen of Antedon bifida. (After P. II. Carpenter.) 

 556.— Ventral view of a radial from a specimen of Antedon bifida. (After P. II. Carpenter.) 

 557.— Two united radials from a specimen of Heliometra glacialis, together with that portion of the 



rosette which is connected to them, \-iewed from the interior of the radial pentagon. (After 



P. H. Carpenter.) 

 558.— The centrodorsal, arm bases, disk, and proximal pinnules of a specimen of Zennmclra 



columnaris from the West Indies, showing the relative proportions of the various parts. 



(After P. H. Carpenter.) 



Plate 6. 



Fig. 559. — The crown and proximal columnals of a very young pentacrinoid larva of Hathrometra prolixa 

 from east Greenland, showing the basals, the orals, the beginnings of the radials (seen as 

 small rhombic plates), and the tentacles. (After Mortensen.) 



560. — Part of the calyx of a young pentacrinoid larva of Bathrometra prolixa from east Greenland, 

 showing portions of two basals and of two orals and, in the center, the right posterior radial 

 (the larger plate to the right) and the radianal (tlie smaller plate to the left); beyond the 

 radial is seen the first commencement of a first primibrach. (After Mortensen.) 



561. — The crown and proximal columnals of a pentacrinoid larva of Hathrometra proli-ta from east 

 Greenland, showing the basals, radials (followed by primibrachs), radianal, and orals, and 

 bringing out well the characteristic shape of the last named. (After Mortensen.) 



562. — Oral view of a pentacrinoid larva of ITathrometra prolixa from east Greenland in which the 

 first brachials have formed, showing the orals, radianal, and radials; the primibrachs have 

 been removed. (After Mortensen.) 



563. — The crown and proximal columnals of a young pentacrinoid larva of Hathrometra prolixa, 

 showing the basals, radials (followed by the primibrachs and first brachials), orals, and 

 radianal. (After Mortensen.) 



564. — Lateral view of the crown and proximal columnals of a young pentacrinoid larva of Hathro- 

 metra prolixa from east Greenland, showing the relationships of the basals, radials, orals, 

 primibrachs, and succeeding brachials. (After Mortensen.) 



Plate 7. 



Fig. 565. — The calyx of a specimen of Marsupites americanus from Mississippi in (a) lateral and in (ft) 



dorsal view, showing the basals (B), the central plate or centrale (C), the very large infra- 



basals (/), and the radials (R). (After Springer.) 

 566. — The infrabasals (underbasals), basals, and radials of a specimen of Metaainus nobilia hom 



southwestern Japan from which the column and the arms have been removed. (Drawing 



by the author.) 

 567. — The isolated circlet of infrabasals of a specimen of Metacrinm nobilis from southwestern Japan, 



viewed ventrally (a), laterally (6), and dorsally (c). (Drawing by the author.) 

 568.— Section through the cah-x and arm bases of a spec imcn of .Mctacrinus nobilis from southwestern 



Japan, showing the circlet of infrabasals in place and their relationship with the other 



elements of the calyx. (Dra\ving by the author.) 

 569. — Xhe centrodorsal of a verj' young specimen of Antedon mediterranea from Naples, surrounded 



by the three infrabasals; a single basal is also shown, near the bottom of tJie figure. (After 



Bury.) 

 , 570.— Dorsal view of the centrodorsal and infrabasals in a young pentacrinoid larva of Antedon medi- 

 terranea from Naples. (After Bury.) 



