52 -Veit Brecher Wittrock. 



Sterile specimens are of the same dimensions as fertile ones. 



Affinities and Differences. This species has a near relative in P. kcu-ennis 

 nob. The differences are as follows (not counting the considerable difference as 

 to size, P. ceqnalis nob. being twice as big as P. Jcctvetisis nob.): the inclosed 

 spores are in P. cequalis nob. proportionally less swollen and shorter than in P. 

 Icewensis nob.; the spore-bottoms are rounded in P. ceqitalis nob., but abrupt in 

 P. TcLwensis nob.; the spores are branchless in P. cequalis nob., in P. Tictvensis nob. 

 they often support branches; the rhizoïd is in P. œqualis nob. generally only rudi- 

 mentary, in P. /ieM;e«s/s nob. it consists of one whole cell; not to mention several 

 smaller differences. P. cequalis nob. is less nearly related to P. sttmatrana (v. 

 Mart.) nob. The differences are noted under P. stdiiatrana (v. Mart.) nob. 



3, PithoplLora kewensis nob. 



Exaicc. WiTTR. à XoRDST. Alg. p]xsicc. Fase. I, n:o ?59. 



Diagmms: Principal filament of the cauloïd part of the tliallus in 

 fertile specimens on an average 59 ,14 thick, with solitary branches 

 of only one degree (rarely of two); spores single, partly inclosed, 

 partly terminal; the inclosed spores cask-shaped, but more elongated, on an 

 av. 81 (.1 thick and 205 n long; the terminal spores cask-shaped with 

 the upper end conical and the top somewhat rounded, on an av. 88 ^ 

 thick and 219 n long; the rhizoïd part of the thallus as a rule unicel- 

 lular. — Plate 1, fig. 8; pi. 2, figs. 1—12; pi. 3, figs. 1—9; pi. 4, figs. 

 2—11; pL 5, figs. 9, 10. 



[P. gracilis et elougata, filo principali partis thalli cauloideœ speciminum fer- 

 tilium circa 50 ;i crasso, ramos primi solius ordinis (raro secuudi etiam ordinis) so- 

 litarios emittente; sporis solitariis, vel inclusis vel terminalibus; sporis iuclusis elon- 

 gato-orculaîformibus, c:a 81 ,« crassis et 205 i-i lougis; sporis terminalibus orculœ- 

 formibus, sursum brevi-acuminatis, apice subrotundato, c:a 88 /( crassis et 219 ,« 

 longis; parte thalli rhizoidea plerumque unicelhdari.]. 



Locality. P. hu-custs nob. is found by me in the Tropical Aquarium or the 

 so-called Waterlily-house at Kew in England. •) It was found with spores during 

 my whole sojourn there, from the 3:rd to the 25:th of August 1872. — As is men- 

 tioned before, I think that the plant is introduced here from a tropical country, 

 probably from South America. (See on this par. 7, pag. 46, 47.) 



General Description. Fertile specimens. Cauloïd part of the thallus. 

 This part is always branched, though sometimes but slightly. In general the cells 

 only of the principal filament develop branches; all the branches are then of the 

 l:st degree. Sometimes the branches of the l:st degree, especially the lowest 

 ones, develop branches of the 2:d degree, though mostly but few. Regard- 

 ing the different strength and nature of the branches of the l:st degree, 

 the following 6 types may be distinguished. In the l:st type the branches are 



') I think it worth inquiry, whether jilauts belonging to this order may not be found 

 also in aquaria for tropical plants on the continent. 



