EXPLANATION OF PLATES. 



The figures of Plates 1-12 were drawn with the aid of a camera lucida using 

 different combinations of the Bausch and Lomb lenses. All the mature 

 bulbils were drawn with the same magnification, namely 4 mm. objective 

 and 3 eye piece, and for the stages of development of the bulbils, 4 mm. objec- 

 tive and 12 eye piece were used. The plates have been reduced in reproduc- 

 tion about three-quarters. 



