BY G. I. PLAYFAIR. 339 



This interesting flagellate combines, in itself, some of the char- 

 acteristics of Volvox, Eudorhia, and Chlamydomonas. The like- 

 ness to Volvox is more apparent than real. The organism looks, 

 at first sight, exactly like a minute Volvox^ with relatively large 

 cells. No trace of parthenogonidia was observed, however, which 

 are almost always present in Volvox, and the construction of the 

 ccenobium is entirely different. The latter is hollow, and built 

 up of a single layer of Chlamydomonadine cells of the Pteromonas- 

 type, having a loose membranous investment. These are so 

 closely adpressed as to show, generally, a regular even margin in 

 optical section; but ccenobia were observed (Pl.xliii., f.ll) in 

 which the component cells had worked loose, the ccenobium 

 being gloeocystiform and irregular at the edge. The peripheral 

 cells, however, have the same relative position to the membrane 

 as in the type — there is no integument to the ccenobium other than 

 the loose investing membrane of the cells. In this, Volvulina 

 differs from Eudorina and Pandorina. Nevertheless, it is like 

 them in its vegetative multiplication. Each cell, when mature, 

 forms an 8-16-32-celled daughter-ccenobium. The latter are set 

 free by the breaking up of the mother-coenobium, and the solu- 

 tion of the membrane of the mother-cell. Such broken coenobia 

 were noted (cell, matric. diam. 36, ccen. filial. 24, cell. 3-4 ju) in 

 which it could be noted that there was a single layer of cells 

 without any investing mucus or membrane. 



Genus V o l vox (Linn.) Ehr. 

 Volvox tertius Meyer. 



Syn., Volvox Bernardii Playf., Biol. Richm. R., p. 106, PI. ii., 

 f.5-11. Too late for correction, I came across a casual note by 

 Lemmermann in Plankt. Schw. Gewass., p. 105, on Volvox. He 

 says, " V. aureus Ehr., and V. tertius A. Meyer,* seem in many 

 ways to be interchangeable with one another, as they both pos- 

 sess round cells; these in V. aureus Ehr., are connected with one 

 another by protoplasmic threads, in V. tertius A- Meyer, on the 

 other hand, they are not." As the absence of these threads is 



* Janet, Le Volvox, p. 143, gives the reference: Arthur Meyer, Die 

 Plasmaverbindungen und die Membran von Volvox glohator, aureus, und 

 tertius mit Rlicksicht auf die Thiereschen Zellen. 1896. 



