21,1 Shaw: Merrillosphaera 119 
tiated in early embryonic stages,!* which sink from positions in 
the layer of somatogenic cells into positions directly within the 
coenobium. They develop to relatively large size before seg- 
mentation. Sexual reproduction by oospores formed from oogo- 
nidia which are smaller and more numerous than the gonidia and 
usually borne in female coenobia, and antheridia formed from 
androgonidia which are smaller and more numerous than the 
oogonidia and borne in male coenobia. Antheridia in the form 
of sperm bundles or platelets that may be more or less cupped. 
Spermatozoids elongate, probably with terminal cilia. 
The type species of this genus is Volvox carteri Stein, based 
on Volvox globator Carter, non Ehrenberg, described by Carter 
in Bombay, India. The first variety of the species to be de- 
scribed in sufficient detail to supply the essential diagnostic 
characters of the genus is Merrillosphaera carteri (Stein) Shaw 
var. manilana Shaw, described in this paper from material col- 
lected about Manila, Philippine Islands. Other forms are: Var. 
typica Shaw based on Carter’s description of the Bombay mate- 
rial; var. weismannia (Powers) Shaw based on Volvox weisman- 
mia Powers described from material obtained in Missouri, North 
America; and species migulae Shaw based on the description by 
Klein under the name Volvox aureus of material obtained from 
Karlsruhe, Germany. * 
Other species are: A somewhat doubtful one, Merrillosphaera 
tertia (Meyer) Shaw (Volvoxz tertius Meyer) described from 
Marburg, Germany, and M. africana (West) Shaw (Volvoz afri- 
canus West) described from Albert Nyanza, Africa, and reported 
by Shaw from the Philippine Islands. 
MERRILLOSPHAERA CARTER! (Stein) comb. nov., var. TYPICA var. 
nov. Plates 7 and 8. 
Volvox globator Carter, non Ehrenberg, in Ann. & Mag. Nat. Hist. 
III 3 (1859) 2-5, 18, 19, pl. 1, figs. 1, 3, 4, 7, 8, and 10. i 
Volvox carteri Stein in Der Organismus der Infusionsthiere. Leipzig 
3* (1878) 1384. 
“It might more properly be said that the somatogenic cells are differ- 
entiated from the gonidia at a very early stage of the embryonic develop- 
ment of the coenobium, and that they become distinguishable by continuing 
to divide while the reproductive cells cease dividing and begin to grow. 
The view expressed by Harper (’18, p. 163) that Volvor “shows vegetative 
totipotence and equivalence of its cells in the growth of the colony” is 
obviously not applicable to any of the species of Merrillosphaera. More- 
over, it appears likely that the gonidia in the latter genus will be found 
to be representative of segments in the 8- or 16-celled stage of development, 
and that they become differentiated when those segments have further 
divided two or three times. 
