2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL.98 



that the water was salt, by seepage or other admixture from the sea. 

 The plants found indicate on the contrary that it is at least nearly 

 fresh, at any rate near the surface and in shallows, though probably 

 heavily polluted with nitrogenous matter from the bird colonies. The 

 bulk of the material was of Myxophyceae, which is appropriate under 

 such conditions, and apparently great masses of Lyngbya versicolor 

 must have been present at least near the shore. This is not a definitely 

 marine species. With it were other Myxophyceae of cosmopolitan 

 habits. In sparing amounts an undeterminable CJwra appeared. 

 Finally, four desmids were found in considerable numbers, one in 

 particular (Cosmariinn clip per tonensis) which the writer inclines to 

 treat as new. It should be observed that these species of desmids 

 (which are as a group intolerant of salt) showed rather weak surface 

 markings and considerable irregularity, so that perhaps they were 

 adapted to slightly brackish conditions. This is supported by the 

 presence of the only phanerogam associate, Najas marina, which is 

 normally an inhabitant of brackish water. No hydrometer readings 

 were made, unfortunately. 



The algae of Old Providence Island, Colombia, off the Nicaraguan 

 coast, were collectively quite in accord with what would have been 

 expected in any productive locality in the Gulf of Mexico and adja- 

 cent waters. One minute encrusting Fosliella was particularly attrac- 

 tive and exhibited a type of variation not known in F. farinosa or the 

 group to which it belongs, so it is described as new. These add a few 

 welcome records to an unexplored section of the Atlantic Central 

 American coast. Apparently material from various spots were min- 

 gled, so it is impossible to indicate exactly the habitat in the appended 

 list. 



SYSTEMATIC LIST 



MYXOPHYCEAE 



CHROOCOCCACEAE 



Chroococcus turgidus (Kiitzing) Nageli 



Occasional among filamentous algae in the lagoon, Clipperton Is- 

 land, Mexico (Schmitt 21), July 21, 1938. 1 



Microcystis flos-aquae (Wittrock) Kirchner 



Colonies infrequent among filamentous algae in the lagoon, Clipper- 

 ton Island, Mexico (Schmitt 21), July 21, 1938. 



1 The collection numbers were assigned by the author after the material had 

 been sorted and mounted. 



