212 



often getting a penicilliform appearance. The cells in these 

 branchlets are nearly cylindrical, being in the middle of the 

 branchlet about 80 // long and 25 // broad. 



The chromatophores (Fig. 194 a, b, c) are parietal, consisting, 

 in the quite young cells, of shorter or longer irregularly shaped 

 plates ; in more developed cells they have the shape of a small 

 roundish disc and finally in the old mature cells we find them 



like the thin, sinuate ribbons 

 generally found in this group 

 of algae. 



One nucleus is present in 

 each cell. Hairs are wanting; 

 at least I have not found any 

 in my material. 



Male (Fig. 196) and female 

 (Fig. ] 95 b) plants as well as 

 tetrasporic plants (Fig. 195 a) 

 occurred in the collection. Jud- 

 ging by the rather scarce ma- 

 terial at hand the tetrasporic 

 and the female plants are the 

 most vigorously developed and 

 also most common, while the 

 antheridial plants seem to be 

 more slender and rare. 



The tetrasporangia (Fig. 195 

 a) are spherical, lining the upper 

 (inner) side of the filaments in 

 Fig. 197. Mesothamnion caribaeum the branchlets, issuing singly at 

 nov. spec. Two procarps with tri- the upper end of each joint. 

 chogynes. a, with adherent sperma- ,. J . , 



tium. (About 200 : 1). They are tetrahedrally divided. 



Their diameter reaches a length 

 of about 45 /i; their wall is about 2,5^ thick. 



The antheridial stands (Fig. 196) are pedicellate, subcylindric- 

 al bodies about 75 // long and 40 // broad; the stalk is about 

 30^ long and 12 /j. broad. They are found in the same places 

 as the tetrasporangia, lining the upper side of the filaments. 

 They originate from a cell which is richly filled with protoplasm. 

 This cell is divided by transverse walls into 3 4 superposed 

 cells (Fig. 196 c). These increase in size and, with the exception 

 of the lower part of the basal cell which forms the stalk, are 

 divided gradually by several anticlinal and periclinal or more 



