OP ARTS AND SCIENCES. 91 



In examiniiig some material of Dlctijota ciliata which was collected 

 at the same time and ijlace as that of Zonaria variegata, I came across 

 an interesting point regarding the tetraspores to which it seems worth 

 while to call attention. The tetraspores in the material examined 

 were apparently not fully developed, at least no typical division into 

 four was seen. Very often, however, a vertical wall divided the upper 

 cell of the tetraspore in half (Fig. 7), which was presumably prepara- 

 tory to dividing again at right angles to form the quadripartite condi- 

 tion usually found. But this simple bisection was not the only form 

 of division observed. Frequently irregularly placed walls were found 

 which were not compatible with a division of the spore into four parts. 

 In Figure 8, an extreme case is shown. There are apparently two 

 basal cells, somewhat distorted, and in the tetraspore itself, starting 

 from a central cell are several radial septa which divide the spore 

 into a considerable number of parts. The septa were not always to 

 be reduced to such a definite plan ; there were several cases like those 

 shown in Figures 9 and 10, where the divisions were so irregular that 

 no order could be found in their arrangement. The significance of 

 this multiple division could not be explained with only alcoholic mate- 

 rial ; it was too frequent, at least in the specimens I examined, to be 

 an accident. A study of the living plant would be necessary to deter- 

 mine certainly if these bodies were really tetraspores, and not some 

 form of gemmce. 



In conclusion, I wish to express my great indebtedness to Professor 

 Farlow, not only for the use of his material, but also for his kind as- 

 sistance throughout the course of my work. To Mr. W. S. Wads- 

 worth I am also obliged for specimens of Zonaria variegata sent by 

 him from Bermuda. 



Crtptogamic Laboratory, 



Harvard University. 



