EXPLANATION OF PLATES. 

 PLATE 1. 



FIG. 514. A young specimen of TfoJopus rangii from Cuba attached by a spreading base after the man- 

 ner of a sessile barnacle. (Adapted from P. H. Carpenter.) 



515. The topmost columnal in a specimen of Metacrinus rotundas from southwestern Japan. 

 516. A series of columnab from the center of the column of a species of Platycrinus, illustrating the 



short spirally arranged type of columnal derived through the bourgueticrinoid type, viewed 



from the broader side (a), from the narrower side (6), and from the end (c). (Drawing by 



the author.) 

 517. A fully grown specimen of Holopus rangii from Barbados attached by a thick unjointed column 



after the manner of a stalked barnacle. (Adapted from P. H. Carpenter.) 

 518. A portion of the dried column of a young pentacrinoid larva of Antedon bifida from England, 



showing the long bourgueticrinoid columnals, and the annulua about the center of each. 



(After W. B. Carpenter.) 

 519. The twenty-third and twenty-fourth columnals in the stem of a pentacrinoid larva of Hathro- 



metra prolixa from East Greenland in which the first brachials have formed, and in which 



the radianal is still present. (After Mortensen.) 

 520. Columnals from the center of the column of a pentacrinoid larva of Hathrometra sarsii. (Aftet 



Mortensen.) 

 521. Columnals from the center of the column of a pentacrinoid larva of Antedon petasus. (After 



Mortensen.) 



522. Long bourgueticrinoid columnals from about the center of the stem of a fully grown penta- 

 crinoid larva of ffalhrometra garni from Norway, in lateral (a) and in end (6) view. (After 



M. Sars.) 

 523. The upper portion of a columnal from a pentacrinoid larva of ITathrometra prolixa from east 



Greenland, in end (a) and in lateral (6) view. (After Mortensen.) 

 524. Half of a columnal from a pentacrinoid larva of Hathrometra sarsii from Norway, showing the 



expanded end and the interlocking teeth along the fulcral ridge. (After M. Sara.) 

 525. The articular face of a columnal of Proisocrinus ruberrimus from about the middle of the 



column, showing the radial crenellse. 

 526. Columnals from the middle of the stem of the pentacrinoid larva of neliomctra glacialis. (After 



Mortensen.) 



PLATE 2. 



Fio. 527. The column of a specimen of Bathycrinus maximus from the Indian Ocean, showing the pro- 

 gressive variation in the type of the columnals from near the proximal to near the distal 

 end; (a) the distal and (6) the proximal portion. 



528. Lateral view of a young specimen of Comatilia iridometriformis, showing the iuterradials. 



(Drawing by the author.) 



529. Ventral view of a young specimen of Comatilia iridometriformis, showing the interradials. 

 (Drawing by the author.) 



530. The inner ends of the orala of a very young pentacrinoid larva of Hathrometra sarsii from 

 Norway. (After M. Sars.) 



531. Diagram illustrating the progressive resorption of the dorsal pole of the centrodorsal, and its 

 effect upon the arrangement of the cirri. (Drawing by the author.) 



383 



