168 SOME NEW OK LESS KNOWN DESMIDS FOUND IN N. S. WALKS, 



Genus P e n i u m Breb. 



P. GRACILLIMUM, 11. sp. (T.iii. f.l). 



Pen. angustum, elongatum, 8-10 plo. longius quani latum, medio 

 sinu acuto minuto vix constricbum, apicem versus levissime 

 attenuatum; apicibus truncatis; lateribus rectis, parallelis. Semi- 

 cellulae utroque margine denticulationibus 2 minutissimis in 

 partes 3 divisae, denticulationibus noii semper perfecte regulariter 

 dispositis. Membrana achroa, longitudinaliter punctato-striata; 

 s-riis 8-10. 



Long 116-156; lat. 15^. 



Coogee. 



A near neighbour of P. margarltaceum Ehr., see Kalfs, T.'25, 

 f.le, and Wolle, Desm. U. S. T.5, f.ll, from which its perfectly 

 straight and parallel sides, colourless membrane, and marginal 

 denticulations serve to distinguish it. 



P. PACHYDERMUM, n.sp. (T.ii. f.6). 



Pen. curtum, crassum, cylindraceum, diametro subduplo 

 iongius, medio sinu acuto minuto vix constrictum. Semicellulae 

 subcouicae, angulis inferioribus rectis, lateribus e basi verticali- 

 bus, adscendentibus, tum repente ad apicem convergentibus, 

 apicibus late rotuiidatis. Membrana achroa, glabra, crassa. 



Long. 84-; lat. 37/i. 



Centennial Park. 



The congeners of this species belong to the globose group of 

 large Peiiium forms such as P. australe Rac, P. lagenaroides 

 Roy,* P. cucurbitinum Biss. jS suhpolymorphum Nord.f The 

 last-named is nearest to it in outline. 



P. AUSTRALE Rac, Desui. Ciast. p. 7-8, T.l,f.ll. (T.ii. f.5\ 



Long. 66, 66, 74, 75; lat. 37, 43, 42, 48/i. 

 Collector, Auburn, Centennial Park. 



* Desm. Windermere, T.5, f.6. 

 t Fr. Alg. N. Z. T.7, f:20. 



