Maskell. — 0?? the Neiv Zealand Desmidiese. 257 



visible in any case, beyond, that is, the folds due to the bursting of the 

 cell-wall, which were easily recognizable. Consequently, I could only infer 

 that the fronds had undergone self-division previous to conjugation ; and on 

 this supposition those in which the inequality was but slight would have 

 simply missed conjugation and were growing in the ordinary way. This 

 being the case, if I am right, it results that each pair of segments in C. 

 acerosum produces a zygospore, and therefore each whole frond produces 

 two zygospores ; but the process differs from that of C. selenceum and C. 

 ehrenbergii in this, that the fronds do not shut themselves up in pairs in 

 mucus, but are all enveloped in the same envelope. 



Certainly, I cannot say that I saw any fronds dividing, for the process 

 had already begun, and was in full swing when first seen. But I am unable 

 to account in any other n /ay for the curious inequality of the arms. 



As C. acerosum has only a suture at the middle, and no secondary sutures, 

 the bursting of the cell- wall anywhere but at the middle cannot be explained 

 as in C. intermedium. Penium margaritaceum and other plants also open un- 

 equally, but they too have secondary sutures. 



Closterium Kneaticm, Ehrenberg. 



This is another of the plants observed conjugating. There is nothing to 

 distinguish it from the English species. 



Closterium diance, Ehrenberg. 



Also observed conjugating. 



I add a figure (20) of Scenedesmus quadricauda, to show the three bristles 

 sometimes observable. 



Also two figures, 21 and 22, as specimens of the curious monstrosities 

 of growth often seen amongst Desmidiese, a family generally of such re- 

 markable symmetry of form. Fig. 21 is Tetrachastrum (Holocystis) incisum ; 

 fig. 22 is Docidium clavatum. 



Nominal List of DESMIDIEiE eepokted from New Zealand up to 1882. 



An asterisk in this list marks the species described by me as neio in the foregoing and my 

 previous paper (vol. xiii., 1880, p. 297); a dagger marks those described as new by Dr. 

 Spencer in his paper (vol. xiv., pp. 295, 296) ; and a double dagger those reported by 

 Dr. Spencer in the same paper, but not new. 



[Note. — I include also Docidium (Pleurot&nium) ovatum, of which I find the following 

 notice in one of Professor Nordstedt's papers — " Htec species quoque in Brasilia et Nova 

 Zealandia lecta est ;" but I do not know the plant.] 

 Hyalotheca dissiliens. Sphserozosma excavatum. 



dubia.ft filiforme. 



Aptogonum undulatum.* pulchrum.t t 



Desmidium aptogonium. vertebratum. 



swartzii. Micrasterias ampullacea.* 



17 



