i ;8 
W. B. Grove. 
The young colonies measure 55 x 45/a, the mature ones 170 x 140/a; 
they consist of 32, rarely of 16 cells, arranged in five or four distinct 
zones respectively. 
Professor Henfrey described in 1856 (8), from a pond in 
Middlesex, what he called, (probably on account of its shape) 
Pandorina Morion , but the shape of the cells in his figures makes it 
clear that he had before him Eudorina. The colonies were ellipsoidal, 
thediameters being about as 9 or 10 : 7 ; no posterior mamillations are 
shown. The globose cells are figured as all alike in size in each 
colony, but in other respects, in shape and zonal arrangement, they 
resembled the Harborne specimens. 
In 1857, Carter (7) found in tanks at Bombay, in May and June 
when they were nearly dried up, a quantity of Eudorina elegans of 
a distinctly ellipsoidal shape; each colony had 16 or 32 similar cells, 
and many were mamillated at the posterior end; they varied from 25 
to 140/x long according to age, and always swam with one end fore¬ 
most, rotating as frequently in one direction as in the other. The 
largest eye-spots were in the anterior cells. In the 32-celled stage, 
in certain cases, he found the four anterior cells to divide into 64 
pyriform antherozoids with a mass of cilia turned to one side, the 
two original flagella and the original large eye-spot still persisting. 
The remaining 28 cells of the colony he regarded as female cells, 
and he considered that fertilisation took place within the colony, the 
antherozoids becoming dissociated and swimming about singly 
within its gelatinous envelope. The antherozoids and oospheres 
resembled those described above, except that the former are stated 
to be colourless at both ends, and faintly green in the middle. The 
actual fertilisation was not seen, and these observations have never 
been confirmed. 
In 1894, Shaw described (14) a new genus Pleodorina, agreeing 
in most respects with Eudorina but having cells of two types, 
“ vegetative ” and “ gonidial,” situated respectively in the anterior 
and posterior parts of the colony. He assigned to it a species, P. 
californica, in which the number of cells is given as 128 (rarely 64) 
the vegetative cells constituting approximately the anterior half of 
the colony (Fig. 6). The cells were all alike at first escape, but 
when mature the gonidial cells measured 2-3 times the diameter of 
the vegetative cells. The maximum diameter of a colony is stated 
to be 175-300/a, and the colonies, which revolved clockwise, were 
globular or broadly ellipsoidal. This species, originally found in 
California, has since been discovered in Illinois and Indiana, and 
