Maskell. — On New Zealand Desmidiese, 299 



rely greatly upon his own judgment and observation, and if these should not 

 unfrequently lead him into error he may at least feel relieved from respon- 

 sibihty. 



As this paper purports to be only a catalogue, and the Desmidieae have 

 already received much attention elsewhere, I need not stop to characterize 

 the family here, beyond simply quoting the description given by the " Micro- 

 graphical Dictionary :" — " A family of Confervoid Alg£e, consisting entirely 

 of microscopic flexible organisms inhabiting fi-esh water.'" In this general 

 description they differ from the Diatomacess in the character of " flexi- 

 bility," as opposed to " brittleness." Long considered to be animals, (by 

 Ehrenberg and others), they are now universally recognized as plants. 



It will be seen by the following list that I believe I have observed at 

 Christchurch sixteen genera of Desmidie^ proper, containing sixty species. 

 I say "proper," because there is also the genus Pediastrum, of which three 

 species are common here ; but as I think this is not really one of the family, 

 I have paid less attention to it. I have added the three species of Pedias- 

 trum to the list, as the genus is usually referred to in works on the Desmi- 

 dieae, but probably several more species may occur here. 



Of the sixty species of true Desmidie^ in the list, six are as I think new 

 or undescribed, and there are also two species of the genus Ankistrodesmus, 

 which I could not identify. The lower forms of life, particularly pond-Hfe, 

 seem to be pretty much the same all over the world, and I ought to give 

 here some explanation of my reasons for venturing to add some six new 

 species to those already known. If I am rightly informed, in the kindred 

 family of the Diatomacete only one new species has for several years been 

 described in New Zealand, (of the genus Nitzschia, by Mr. J. Inglis, lately), 

 and it may be thought unlikely that in the Desmidieae there should be 

 greater variety. For this reason I think it well to explain why the six plants 

 just referred to seem to me not referable to any known species (always 

 remembering what I said just now as to the dearth of works of reference 

 here.) 



The Desmidieae have two modes of propagation: — 1. By conjugation, 

 or the union of two separate plants producing between them what is called 

 a " zygospore." 2. By division, where each frond separates into two parts, 

 and in the process of separation two new parts grow between the old ones, 

 until, as the new segments attain the size and form of the old ones, com- 

 plete separation takes place, and each old segment floats away accompanied 

 by its new " half." Now, undoubedly, as Mr. Archer remarks,* in order to 

 be absolutely certain as to a species, it ought to be followed throughout all 

 its stages, that is, from the production of a " zygospore," through full 



* " Quart, Jour. Mier. Science," Vol. II., New Series, 1862, p. 236. 



