384 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



PLATE 3. 



FIG. 532. A small pentacrinoid larva of Hathrometra prolixa from East Greenland, showing the central 

 annulus in the columnals and, in the crown, basals and orals. (After Mortensen.) 



533 A pentacrinoid larva of Anledon mediterranea from Naples, showing the interrelationships of 

 the various parts. (Adapted from Chadwick.) 



534. The distal portion of the column and the root of a very young pentacrinoid larva of Hathro- 

 metra sarsii from Norway, showing the attachment by a digitating terminal stem plate to a 

 columnal of Rhizocrinus lofotensis. (After M. Sars.) 



535. The distal portion of the column of a pentacrinoid larva of Hathrometra prolixa from east 

 Greenland, showing a digitating terminal stem plate. (After Mortensen.) 



536. The attachment of a fully grown pentacrinoid larva, of Hathrometra sarsii from Norway by a 

 typical digitating terminal stem plate and a short radicular cirrus. (After M. Sars.) 



537. The root of a young pentacrinoid larva of Hathrometra sarsii from Norway, showing the digitat- 

 ing terminal stem plate. (After M. Sars.) 



538. The distal columnals and attachment of a young pentacrinoid larva of Hathrometra prolixa 

 from East Greenland in which the radials are j ust beginning to form, showing the commence- 

 ment of the digitating form of terminal stem plate. (After Mortensen.) 



539. The distal portion of the column of a young pentacrinoid larva of Hathrometra sarsii from 

 Norway, showing the attachment, by a digitating terminal stem plate, to a Rhabdammina 

 abyssicola and, at the third columnal beyond, a second attachment by radicular cirri. 

 (After M. Sars.) 



540. A young pentacrinoid larva of Hathrometra sarsii from Norway, showing attachment by a 

 digitating terminal stem plate, beyond which are two attachments by radicular cirri, and 

 still further out unattached incipient radicular cirri. (After M. Sars.) 



541. Incipient radicular cirri on the columnals of a young pentacrinoid larva of Hathrometra sarsii 

 from Norway; the columnals shown are the twenty-third and twenty-fourth above the 

 terminal stem plate. (After M. Sars.) 



PLATE 4. 



Fio. 542. Oral view of a very young pentacrinoid larva of Hathrometra prolixa from East Greenland, 



showing the orals. (After Mortensen.) 

 543. Young pentacrinoid larva of Antedon bifida showing the terminal stem plate, the columnals 



in process of formation, the basals, the orals, and, in the angles between the basals and the 



orals, the beginnings of the radials. (After Wyville Thomson.) 

 544. The crown and proximal columnals of a very young pentacrinoid larva of Hathrometra prolixa 



from East Greenland, showing the basals and orals. (After Mortensen.) 

 545. A pentacrinoid larva of Heliometra gladalis at the time of the first formation of the cirri. 



(After P. H. Carpenter.) 

 546. A young columnal consisting of a central annulus only in a peutacrinoid larva of Antedon 



mediterranea from Naples. (Adapted from Bury.) 

 547. Oral view of an early pentacrinoid larva of Compsometra loveni from Port Jackson, New South 



Wales, showing the orals and, beyond them, the basals. 

 548. Oral view of a young pentacrinoid larva of Comactinia meridionalis from Yucatan, just after 



the appearance of the radials. 



PLATE 5. 



FIG. 549. A radial radial from a specimen of Promachocrinus kerguelensis from Kerguelen Island viewed 

 from the interior of the calyx (a) and laterally (6). (After P. H. Carpenter.) 



550. Dorsal view of a radial radial of a specimen of Promachocrinus kerguelensis from Kerguelen 

 Island. (After P. H. Carpenter.) 



551. An interradial radial from a specimen of Promachocrinus kerguelensis from Kerguelen Island 

 viewed from the interior of the calyx (a) and (6) laterally. (After P. H. Carpenter.) 



