522 NEW AND RARE FRESHWATER ALGA, 



Long. oO, lat. 2-3/7.. Auburn; Lismore (350). 



A minute and very slender species, rostrate in front and \'ery 

 acute behind; membrane very delicate. Chloroplast also very 

 delicate, homogeneous, parietal, without pyrenoids. A hyaline 

 space, probably containing the nucleus, in the centre of the cell. 

 Stigma very distinct, wick-shaped, some distance down from the 

 apex. Contractile vacuoles not noted. Flagella 2, going off at 

 right angles close to the tip. 



Genus Pteromonas Seligo. 



PterOxMONAs angulosa v. australis Playf. 



Syn., Pt. alata v. australis Playf., Frw. Alg. Lismore, p. 335, 

 PI. 42, f.l4. Pt. alata Seligo, is a synonym, it appears, of Pt. 

 angulosa (Carter) Dang., {Cryptoglena anyulosa Carter, Ann. Nat. 

 Hist., 1859, T.l, f.l8a-6'). The side-view (PI. Iv., f.28) is char- 

 acteristic of the type and all its forms, cf. Chodat, Alg. vertes, 

 p. 144, fig. 68 E. 



Forma. (PI. Iv., f.27, 28). 



' Membrana a tergo incisa. Long. 22J, lat. 15/x. Lismore(312). 



Var. 8CUTIF0RMIS, n.var. (PI. Iv., f.29). 



Cellulie membrana oblonga, fronte paullo angustata; lateribus 

 inferne rectis, levissime convergentibus, apicem versus incurvis; 

 apice levissime concavo ; augulis posterioribus rectis ; basi in 

 medio inllata. 



Long. 16, lat. 11; corp. lat. 8/v.. Lismore (344). 



The enveloping membrane is oblong, with straight sides con- 

 \ erging slightly, and drawn together in front, the apex a little 

 concave. Lower angles square, and at the base convex. In all 

 these forms observed here, the chloroj^lasts, though very pale and 

 thin, showed the characteristic cup-shape. No stigma, however, 

 was present, nor pyrenoid. 



Var. VEXiLLiFORMis, n.var. (PI. Iv., f.30). 

 Cellulse membrana fere quadrata; lateribus rectis, parallelis: 

 apice piano; angulis superioribus oblique truncatis; basi convexa; 



