Volvox and Associated Algae from Kimberley. 501 



B. TETRASPORALES, PALMELLACEAE. 



Genus SPHAEROCYSTIS Chodat.* 



Sphaerocystis Poweri, sp. nov. 

 (Fig. 6, and Plates XXXVI, XXXVII.) 



Familiae formae pervariantes, aut (1) familiae plerumque conspicuo 

 perfecte globosae in tegumento gelatinoso hyalino vel sub-flavo 

 involutae ; cellulis 32, raro 8 vel 16, regulariter ad peripheriam 

 dispositis, plerumque omnibus extemplo partitis in sub-familiis 

 similis ellipsoideis 8- (raro 4-), vel 16-, vel 32-cellularum compositis, 

 ad peripheriam aequabilitissime dispositis ; aut (2) familiae magnae 

 amorphae, interdum fere rotundae, plerumque elongatae irregularitae, 

 fere teretes ; cellulis permultis, rotundatis, parvis, in tegumento 

 gelatinoso hyalino ; zoosporis utrobique parvis vel paullum majoribus, 

 ovatis, interdum leviter obliquis ; aut raro (3) familiae botryoidae, 

 sub-familiis pluribus, cellulis minimis in tegumento gelatinoso hyalino 

 irregulariter lobato consociatibus. 



1. Fam. glob. diam.. . 140-1615 p. 



Cell. diam. . . . 6-16 /z; plerumque, 16-20 ^ 



Subfam. . . 1-215 p. x 151 /JL x 108 p 



Zoospor. . . . 4-5 ^ x 7-9 /A; vel 8-9 p. x 10-11 p 



2. Fam. palmell. long. . ad 2-5 mm. 

 Cell. diam. . . 4-10 (-13) p 

 Zoospor., v. supra. 



Found in Pool I only, most abundant in the later stages of each 

 phase, finally forming the bulk of the phytoplankton as the water 

 dried up. 



In the early stages of the pool's existence, among masses of Volvox 

 Rousseletii colonies, small rounded Eudorina-\ike gelatinous colonies 

 containing usually 32, occasionally 8 or 16, cells are fairly common 

 (fig. 6, A). They are distinguished from the Eudorina colonies 

 which are present in the same material by (1) absence of cilia, (2) 



* Wille (1903) and Lemmermann (1915) sink this genus in Gloeococcus A. Braun, 

 but Chodat (1904) contested this, and West (1916, p. 186) accepts Chodat's genus 

 as distinct. As it does not appear that any fresh facts have been added to the 

 knowledge of the two species constituting Braun's genus (cf. Lemmermann, /or. 

 cit., p. 32) which are still described as "incompletely known," and in which there 

 is apparently nothing whatever to correspond to the very characteristic spherical 

 form described by Chodat, West is followed here, and Chodat's genus accepted 

 (see p. 505). Oltmanns (1923, vol. i, p. 243, etc.) also accepts Chodat's genus. 



