MARINE ALGJE OF BEAUFORT, N. C. 489 



Genus 3. Chrysymenia J. Agardli. 

 Chrysymenia, J. Agardh, 1842, p. 105. 



Frond terete or somewhat flattened, hollow in parts or throughout the entire length, 

 sometimes segmented by constrictions, .variously branched, sometimes caulescent and 

 almost solid below with hollow, vesicular, bladderlike lateral branches above; filled with 

 loose jelly; structure cellular, central axis lacking, inner cells large, outer ones smaller, 

 cortical ones minute, scattered filaments sometimes traversing the internal tube; tetra- 

 sporangia scattered over the thallus surface, embedded among the cortical cells, cru- 



Fig. 31. Meristotheca duchassain-yii, showing tetrasporangia 

 and internal structure (diagrammatic) X 30. 



Fig. 32. Meristotheca duchassaingii, showing internal struc- 

 ture and tetrasporangium, X 183. 



Fig. 33. Agardhinula browneee, structure of thallus and 

 cystocarp, X 3- 



Fig. 34. Chrysymenia agardhii, cross section of thallus. 

 XiR 3 . 



Fig. 3$.NitophyUum medium (type), surface view show- 

 ing veins and cells, X 33. 



ciately divided; cystocarps scattered over the frond, fairly conspicuous, hemispherical, 

 opening by an apical pore, fruiting cavity with a trace of a filamentous network or 

 entirely lacking this, gonimoblast arising from the base of the oavity, composed of several 

 coalescent lobes, bearing many rotund carpospores irregularly grouped in masses, 

 somewhat inclosed by a gelatinous covering. 



Fifteen to twenty species in warm seas. Some of the species of this genus resemble 

 in external appearance species of Halymenia, from which they may usually be distin- 

 guished by their structure. In the species of Chrysymenia the frond is hollow or nearly 

 so, the wall consisting of one or two loose layers of large cells surrounded by one or two 

 layers of small cortical cells; there are usually no filaments traversing the cavity. In 



