2 



MEMOIRS OF THE XEW YORK BOTANICAL GARDEN 



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

 termediate or connecting forms, both unicellular and filamen- 

 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 lilaments to 

 almost pure material, of Scijtoneina. Many were troublesome 

 to place and I have created several new sj^ecies. Many genera of 

 Myxophyceae are very much in need of thorough revision. In 

 several instances I am employing established genera as conveni- 

 ences rather tlian 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 comprise in all fifty different genera, probably 

 by far the largest number of genera ever i^reviously assembled 

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

 of The New York Botanical Garden. 



Synechocystis primigenia sp. nov. 



Plate I, figure 1 



Cells perfectly spherical in the resting stage, without visible 

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



Growing on limestone bet\\^een 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 m diam., homogeneous, pale aerugi- 

 nous. 



Growing in a pool about four kilometers north of Mayagiiez, 

 no. 1329 h, type. 



