64 Annals of the South African Museum. 



Two other species of this genus are known, M. Usterianum, 

 Schmidle, from the Philippines and M. palatinum, Schmidle, from 

 Germany. M. hirudiforme is distinguished from the former by 

 being proportionately shorter and in the different character of its 

 extremities ; from the latter by its proportionately greater thickness 

 and by the character of the poles, which are not of greater diameter 

 than the median portion of the cell. 



I have not met with a member of this genus before, and M. 

 hirudiforme is one of the most remarkable blue-green algae I have 

 yet come across. Specimens were carefully stained, but they 

 showed no signs of anything like a definite central-body, and no 

 trace of transverse cell-walls. It may be that Myxobactron is one 

 of the most primitive of the blue-green algae. 



3. Merismopedia glauca, (Ehrenb.) Nag. 



Little Namaqualand. In dam at Pella ; 8.1.09. Among other 

 algae and a species of Chara at Dabainoris ; 11.1.09. 



Cape Eegion between Ceres and Karoopoort. In a spring smelling 

 strongly of sulphuretted hydrogen at Leeuwefontein ; 28.12.08. 



4. Merismopedia tenuissima, Lemm. 



Karoo. Floating in spring smelling strongly of sulphuretted 

 hydrogen at Pappekuil ; 2.12.08. Floating in similar spring at 

 Gansfontein ; 2.12.08. 



Little Namaqualand. In a dam at Kamiebies ; 24.12.08. 



Great Namaqualand. In a cattle-trough at Grundoorn ; 4.2.09. 



Cape Eegion between Ceres and Karoopoort. In a spring smelling 

 strongly of sulphuretted hydrogen at Leeuwefontein ; 28.12.08. 



5. Merismopedia punctata, Meyen. 



Little Namaqualand. In wet mud on the banks of a dam at 

 Pella; 8.1.09. In a dam at Kamiebies; 24.12.08 Dabainoris; 

 11.1.09. 



6. Tetrapcdia glaucescens, (Wittr.) Boldt. 

 Long. cell. 5-5 /.i ; lat. 6 p. 



Little Namaqualand. Among Chara sp. in dam at Pella; 8.1.09. 



7. Gomphosphceria aponina, Kiitz. 



Little Namaqualand. In wet mud on banks of dam at Pella; 

 8.1.09. Dabainoris; 11.1.09. From the latter locality the speci- 

 mens were exceptionally fine. 



8. Microcystis prasina, (Wittr.) Lemm. 

 Diam. cell. 3-36 yii diam. colon. 16-52 p. 



