PLATE XVI. 



Figs. 1-5. Cynthia formosa, Herdman. 

 Figs. 6-9. Cynthia arenosa, Herdman. 

 Fi_-s. 10-12. Cynthia irregularis, Henlman. 



Fig. 1. Cynthia /< - i, from the right side ; natural size. 



Fig. 2. Part of the branchial sac of Cynthia formosa, seen from th- - : magnified 



(Hartn., ob> 4). 

 Fig 3. A -mall portion of the branchial sac of Cynti seen from the inside, 



showing an irregularity ; magnified (Hartn.. obj. 4 (. 

 Fig. 4. Part of the dorsal lamina of Cynthia formosa, showing the marginal languets (/.); 



magnified (Hartn.. obj. 4). 

 Fi^r. 5. The dorsal region of the anterior end of the branchial sac. showing the dorsal 



tubercle (d.t.), the peritubercular area, the preebranchial zone, and part of 



the circlet of tentacles [tn. and tn.'.): magnified (Hartn., obj. 4). 

 Fig. 6. Cynthia i - \ a specimen seen from the right side ; natural size. 



Fig. 7. Part of the branchial sac of Cyntl - . seen from the inside, and showing 



two of the folds (brf.), two interspaces, and part of the dorsal lamina (1.) ; 



magnified (Hartn., obj. 4). 

 _. 8. The dorsal tubercle and peritubercular area of Cynthia arenosa; magnified (Hartn., 



obj. 4). 

 Fig. 9. A small portion of the modified test lining the branchial siphon of Cynthia. 



magnified (Hartn., obj. o). 

 Fig. 10. Cynthia irregularis, from the left side : natural size. 

 Fig. 11. Part of the branchial sac of Cynthia irreavla - n from the inside, and 



showing a fold (br.f. <. and several irregular areas ; magnified (Hartn., obj. 4). 

 Fig. 12. The peritubercular area and dorsal tubercle of Cynthia irret '$; magnified 



(Hartn., obj. 4). 



