34 



L. HILLIS-COLINVAUX 



Fig. 15. A single medullary filament occurs in the node of H. cryptica, and the wall is 

 much thicker in this region than elsewhere. The collar of smallish utricles from the 

 upper segment which would surround much of the exposed filament has been 

 dissected away. Scale bar is 100 (xm. (From Colinvaux and Graham, 1964.) 



the genus received its second monographic treatment by Hillis (1959). 

 A number of new species has been found since then. 



Studies on the structural and functional biology of the genus were 

 begun by the early microscopist Ellis, and for long had the result of 

 producing arguments over whether Halimedae were plants or animals. 



