PLATE XXI 



BASAL ORGANS OF DICTYONEMA FLABELLIFOEME 



1 a, 6, var. conferta 



2 a, &, c, acadica (&, c, juv.) 



3 a, 6, acadica m. f. ruedemanni 



4 a-(Z, ruedemanni 



All specimens are preserved in the collection of Columbia University and 

 are enlarged five times in the figures. The measurements given refer to the 

 length of the entire colony, which is not always represented. 



