2 



MEMOIRS OF THE XEW YOKK BOTANICAL GARDEN 



among nearly related unicellular forms. In many instances, in- 

 termediate or connecting forms, both unicellular and lilamen- 

 tous, occurred, leaving little choice as to the genus with which 

 they should be associated. Some four hundred numbers con- 

 tained specimens, ranging from a few scattered filaments to 

 almost pure material, of Scytonema. Many were troublesome 

 to place and 1 have created several new species. Many genera of 

 Myxophyceae are very much in need of thorough revision. In 

 several instances I am employing established genera as conveni- 

 ences rather than as generic entities, and am not making an at- 

 tempt at revision except in a few instances of modification men- 

 tioned in the text. 



After the death of Dr. Wille I was invited by Dr. M. A. Howe 

 to study the collection. I am proposing in this paper three new 

 genera and two hundred and fourteen new species and varieties. 

 Aside from these, I have identified over fifty species previously 

 described. These comi:)rise in all fift}^ different genera, probably 

 by far the largest number of genera ever previously assembled 

 from any equal area on the globe. The types are in possession 

 of The New York Botanical Garden. 



Synechocystis primigenia sp. nov. 



Plate 1, figure 1 



Cells perfectly spherical in the resting stage, without visible 

 membrane or gelatinous tegument, 0.8-1 n diam., pale aeruginous. 



Growing on limestone between Hatillo and Arecibo, no. 

 1377 h, type ; on the wall of a church, forming, in company with 

 other Myxophyceae, a thin stratum, Sabana Grande, no. 953 h. 



This is the smallest and simplest example of all the known 

 species of the genus. 



Synechocystis Willei sp. nov. 



Plate 1, figure 2 



Cells floating or free among other algae, not forming a stra- 

 tum alone, spherical, 3.5-3.8 \x diam., homogeneous, pale aerugi- 

 nous. 



Growing in a pool about four kilometers north of Mayagiiez, 

 no. 1329 h, type. 



