238 



W. G. KIDEWOOD. 



noted. This relation of the " body " and sliield whereby 

 the plumes are not visible except by dissection is a common 

 one; it is only exceptionally that the " body ^' is so much 

 drawn back as to expose the developing plumes as com- 

 pletely as in text-fig. 6, i>, and in fig. 66 of Plate 7 of the 

 '"Discovery" Expedition Reports/ vol. ii, 1907. 



The post-oral lamella is not well defined until after the 

 fourth plumes have developed. In text-fig. 7, g^ the two 



Text-figitke 7. — Cephalodiscus nigrescens. I'igures illus- 

 tratiug tlie development of the plumes of the buds ; series con- 

 tinued from text-fig. 6. G, H and J represent the collar and 

 appendages (plumes and post-oral lamella) as seen in dorsal view; 

 K and L are single plumes. The fifth pair of plumes are appearing 

 in H, and the seventh in .T. All figures enlarged G2 diameters. 

 For explanation of the lettering see end of paper. 



lateral flaps are complete, but the free edge connecting the 

 two flaps behind the mouth is not yetentire^ and so in making 

 such a dissection as is shown in g and h this part is left with 

 a ragged edge (h, r.e.). The plumes of the first three pairs 

 are elongating and are swelling out so that the base of each 



