614 SOME SYDNEY DESMIPS, 



Var. quadrigeminatum, n.var. 



Paullo minus quam var. nodulatum. Semicellulse angulis 

 basalibus minus acuminatis minus incrassatis, apicibus paullo 

 productis, nodulis prominentibus. A latere visse subglobosae, 

 apicibus paullo productis, nodulis binis. 



Long. 45; lat. 34-36; crass. 25; lat. apic, a fronte 15, a latere 

 14/.. 



Guildford (60), cum priori. 



The fully developed form certainly has only two nodules to the 

 semicell; var. quadrigeminatum seems to be a variation occa- 

 sionally produced, as I have noted, at division. The opposite 

 nodules (in side-view) coalesce later, and the produced apex 

 disappears. This shows that a desmid is not limited to one plan 

 of development. 



Cos. difficillimum, ii. sp. (Plate xiii.j fig. 5). 



Cos. parvum, oblongum, medio sinu lineari profunde con- 

 strictum. Semicellulse subquadratae vel subhexagonse latissimse 

 infra apices, angulis omnibus rotundatis; lateribus e basi levissime 

 divergentibus, apicibus late-arcuatis plus minus truncatis, foveis 

 apicalibus singulis instructis; seriebus 3 punctorum ornatae : — 

 punctis apicalibus 4, exterioribus in cytioderma; medianis in 

 centro 4 et utrinque 2 paullo superne, exterioribus in cytioderma; 

 basalibus 4, utrinque ad isthmum 1, juxta margines 1. A latere 

 semicellulse oblongse, lateribus parallelis, apicibus rotundatis, 

 punctis apicalibus 3, medianis 3 in triangulum ordinatis (non- 

 nunquam 5 divergentibus visis), basalibus 2, ornatae. A vertice 

 late-ellipticse, apicibus late-rotundatis, in medio foveis incrassatis 

 2 et punctis 6 concentrice ordinatis, ad polos punctis singulis. 

 Membrana achroa, glabra, crassa. 



Long. 33-36; lat. 21; crass. 13/x. 



Auburn (26), Botany (37). 



This species is a member of a small group of four characterised 

 by puncta variously arranged. In size it agrees with Cos. difficile 

 Liitk., Desm Oberosterr. T.8, f.4, but differs so much from it in 

 front-, side- and end-views, as well as in the number and arrange- 



