NOTES AND MEMORANDA. 



Pithophoracese— a new Order of Algae.— One of the most im- 

 portant and interesting of recent memoirs contributing to our 

 knowledge of the Algse is that by Dr, Veit Brecher Wittrock, 

 of the University of Upsala, "On the Developmentand System- 

 atic Arrangement of the Pithophoraceae,a nevv Orderof Algse," 

 ('Nova Acta Reg. Soc. Sc. Upsal./ 1877j. This new Order 

 belongs to Chlorophyllophycese, and as yet contains but a 

 single genus Pithophora, Wittr., made up of eight (as yet 

 known) species (with a probable ninth, already partially 

 known to the author). 



As the work is throughout written in English it is the 

 more unnecessary to attempt to give a resume sit any length, 

 though not out of place to draw the attention of our readers 

 thereto in this brief summary. The species belonging to 

 Pithophora, in habit and appearance, very much resemble 

 forms of Cladophora ; in fact, some of them had already been 

 referred by previous algologists to that genus, from which, 

 however, Wittrock shows his new genus to differ strongly. 



The author's first acquaintance with a Pithophora-species 

 was made at the Royal Gardens, Kew, and the plant was 

 collected by him in the Tropical Aquarium or Water-lily 

 House ; he names the species there found P. Kewensis. As 

 the other species known to him emanate from tropical or sub- 

 tropical regions he concludes that P. Kewensis had been 

 introduced from a tropical country, probably South America. 

 In those regions the species known belong to freshwater, 

 none to salt, whilst one was found on humid earth. 



The order is thus characterised : — Chlorophylliferous 

 Cladophora-like freshwater algae, consisting of cells, formed 

 by bipartition of the terminal cell. The thallus having two 

 distinct parts, viz. 1, the cauloid part, developed from the 

 germinated spore upwards, propagative and almost always 

 branched, the branches placed a little way below the top of 

 their supporting cells ; 2, the (morphologically, not physio- 

 logically) rhizoid part, developed from the germinated spore 

 downwards, almost always sterile and branchless, commonly 



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