492 CHEOOCOCCACEAE. 



either between the tide lines or permanently submerged. They are not 

 confined to the sea, but are perhaps even more common in brackish or fresh 

 water. They also occur on moist ground and even on trunks of trees and 

 rocks where rains and atmospheric moisture are their only sources of water- 

 supply. A few of the species of Cyanophyceae that have been found in 

 Bermuda may be mentioned : 



Family CHROOCOCCACEAE. 



Chroococcus turgidus (Kiitz.) Xaeg., a minute one-celled, more or less 

 colonial plant, occurs in brackish pools, commonly associated with other small 

 Cyanophyceae. 



Chroothece Richteriana Hansgirg, forms verdigris-green or dark blue- 

 green gelatinous cushions or crusts on rocks, sometimes at a considerable dis- 

 tance from the sea, as in Church Cave. 



Chroothece cryptarum Farlow, of somewhat similar appearance to the 

 naked eye, also forms crusts or films on rocks in eaves, as at Agar 's Island. 



Gloeothece rupestris (Lyngb.) Bornet, another unicellular form, occurs 

 as a dark or bluish olive-green gelatinous film on moist ground, as at Spanish 

 Point. 



Family OSCILLATORIACEAE. 



Oscillatoria amphibia Ag., a filamentous plant, forms gelatinous masses 

 in brackish pools, often associated with other species of the same genus or 

 class. Several other species of the genus occur in Bermuda. This genus re- 

 ceives its name from the fact that the filaments in a living condition show 

 slow swaying movements, visible under a compound microscope. 



Lyngbya majuscula (Dillw.) Harv., sometimes known as Mermaid's 

 Hair, forms conspicuous slimy intricate mats or tufts that may vary in color 

 from bluish green to blue-black. The individual threads are easily visible to 

 the unaided eye and seem sometimes to attain a length of several inches. It 

 flourishes best in salt water that is little disturbed, as in the ponds of Walsing- 

 ham and in the tide-pools of St. David 's Island. 



Lyngbya confervoides violacea Collins, has been found by Collins to occur 

 in a small pond near Harrington Sound, where it forms a reddish film on 

 decaying algae, in company, it is said, with Lyngbya lutea (Ag.) Gom. and 

 L. semiplena (Ag.) J. Ag. 



Microcoleus chthonoplastes (Mert.) Thuret, representing a genus in 

 which numerous filaments occur in bundles enclosed in a common sheath, forms 

 a bluish green turf or film on littoral soil, on wooden piers, on borders of tide- 

 pools, etc. 



Hydrocoleum comoides (Harv.) Gom. has been found on rocks near low- 

 water mark at Cox 's Bay, Devonshire. In this, as in the Microcoleus, there 

 is a number of threads inside a common sheath, but the number is less. 



