xv, 6 Shaw: CampbeUosphaera 513 



not megalogonidia such as others have mistaken for eggs. It 

 is even questionable whether the connecting filaments shown in 

 Klein's fig. 7 ('89B, Plate 3) really belong there. The material 

 is of a species more nearly akin to V. tertius and V. cartcri than 

 to V. aureus. 



A more completely described species is another by Powers 

 ('07 and '08), from Nebraska and other parts of North America, 

 to which he gave the name V. spermatosphaera.* This species 

 also has rounded somatic protoplasts without protoplasmic con- 

 nections, and the number of the cells has a range like that of 

 CampbeUosphaera. But the dimensions of the coenobia run to 

 much larger sizes, the cells being farther apart. The gonidia, 

 or primary sex cells, are of considerable size in the daughters 

 at the time of birth, though not so large as to indicate their 

 differentiation at such an early period as is characteristic of 

 CampbeUosphaera and the kindred megalogonidiate Volvoceae. 

 The species is characterized by having male coenobia of which 

 all the cells become antheridia (sperm platelets), leaving no 

 somatic cells. 



In my Philippine material there is still another species, ap- 

 parently most nearly related to V. spermatosphaera, awaiting 

 its turn to be described. 5 It is like the foregoing species in 

 many respects, except that the gonidia are smaller at birth, 

 and the antheridia are relatively fewer and formed in the same 

 coenobia as the oogonia. 



A recent addition to the free-celled larger Volvoceae is one 

 described by Powers ('07) from material obtained in Nebraska, 

 and named by Shaw ('16) who proposed it as the type of a new 

 genus under the name of Besseyosphaera poiversi. This species 

 is more like a Pleodorina Shaw ('94) than like a Volvox, the 

 gonidia not being differentiated in the daughters until after 

 birth of the coenobia in which they are formed. The life history 

 of Pleodoriyia calif ornica has been rounded out by Chatton ('11) 

 from the study of material collected in France. A step farther 

 down the scale is the species P. Illinois ensis Kofoid ('98), the 

 simplest of the Volvoceae which have differentiation of repro- 

 ductive from somatic cells. The life history of this species has 

 been given in detail by Merton ('08) from material obtained in 

 Germany. 



4 Originally spelled "spermatosphara," and emended by West ('16). 



s The manuscript of the description of this species is partially prepared 

 and the species assigned to be the type of a proposed new genus under 

 the name Copelandosphaera diasipatrix Shaw. 



