252 W. G. RIDEWOOD. 



4. The Hue of plume-bases iu tlie adult^ when viewed from 

 the front, is an ellipse, incomplete on the upper side (text- 

 fig. 8) ; and the line of the attached edge of the post-oral 

 lamella is another ellipse, similarly incomplete. The two 

 ellipses join where they are incomplete. 



5. Separate accounts are given in this paper of the plume- 

 development in buds of Cephalodiscus hodgsoni, C. 

 dodccalophus, C. nigrescens, and C. gilchristi. 



G. The plumes develop relatively later in buds of C. 

 nigrescens and C. gilchristi than those of C. hodgsoni 

 and 0. dodecalophus. 



Explanation of the Abbreviations employed in Text-figukes 

 2, 3, 4, 6, 7, and 9. 



1, 2, 3, 4, 5, 6, 7. The first, second — seventh pairs of plumes of tlie buds. 

 b. The "body" of the bud. b.s. Tront lobe or main portion of the buccal 

 shield, m. Mouth, or position of mouth so far as can be ascertained iu the 

 dissected preparations, this region being much disturbed during the dissection. 

 p. Pinnules, p.a. Plume-axis. p.l. Posterior lobe of buccal shield, po.l. 

 Post-oral lamella, r.b. Refractive beads in the swollen ends of the plume- 

 axes in C. hodgsoni and C. dodecalophus. r.e. Ragged edge caused by 

 dissection of the part figured from the rest of the bud. r.l. Red line of the 

 buccal shield, s. Stalk of the bud. 



