NEW MYXOPHYCEAE FROM PORTO RICO 



31 



possible to learn much of their life history. What little is knowji, 

 however, is so distinct from any known genns that it becomes 

 necessary to create a new genus for their reception. I am plac- 

 ing it provisionally in the family Chroococcaceae, seemingly ap- 

 proaching the simplest members of the Oscillatoriaceae. The 

 cells divide by fission and are soon separated completely by a 

 thick, lirm gelatinous membrane or tegument, continuous with 

 the general enclosing tegument. 



Nothing is known of the method of ref)roduction, but prob- 

 ably it is by the dissolution of the tegument, freeing the indi- 

 vidual cells, as in other Chroococcaceae, these again evolving 

 new filaments. 



Cyanothrix primaria sp. nov. 



Plate (J, figure 57 



Filaments relatively short, about 300 n long, straight or more 

 or less flexuous, 18-22 |j diam. ; cells discoid, closer together or 

 farther apart according to age, 10-15 n diam., 3.6-5 n long, aeru- 

 ginous, homogeneous ; tegument smooth on the surface, rela- 

 tively thick, firm, homogeneous, hyaline. 



Growing among other algae in Laguna Tortuguero, no. 830 h, 

 type, and 849 c. » 



Cyanothrix Willei sp. nov. 

 Plate 6, figure 58 



Filaments about 200 n long, 9-11 (j diam. ; cells 6-6.5 n diam., 

 3.5-4.5 (J long, homogeneous or very finely granular, pale aeru- 

 ginous ; tegument almost transparent, about 2 n thick, smooth. 



Growing among other algae in Laguna Tortuguero, no. 830 e, 

 type, and no. 844 e. 



Cyanothrix WiUei resembles C. primaria very closely but is 

 only about one-half as large as that species. No intermediate 

 sizes were observed and although it is possible for a species to 

 vary as much as this from generation to generation, it seems 

 best to keep these two separate and await the accumulation of 

 data on this point, when an accurate decision as to their dispo- 

 sition may be arrived at. 



Pleurocapsa epiphytica sp. nov. 



Plate 6, figure 59 



Thallus very diminutive, 25-^0 p diam., 12-16 [\ (rarely 20 m) 

 thick; basal portion composed of angular cells, 3.5-5 n diam.. 



