Jennings — Two New 8pecies of Phycopeltis, Neio Zealand. 759 



together, and the growth of the plant proceeds in some other direction 

 where there is no resistance. 



The youngest plants observed are minute circular discs in 

 which a trace of four radial walls is distinguishable. At an older 

 stage these radial divisions may be seen growing from the margin 

 inwards, sometimes again in multiples of four, but more often ii-re- 

 gularly. Tangential divisions appear later, but the disc is distinctly 

 divided into radial segments before the cross-walls divide them into 

 cell-rows. Some botanists speak of these plate-like algse as composed 

 of approximated cell-rows, as if the filament were the primitive type. 

 If this were so, we should expect the earliest stages of development to 

 be in the direction of forming cell-rows, as in the germinating spore 

 of filamentous algae generally. 



It would not perhaps be safe to argue that the ancestors of the 

 trichoid Trentepohlias were peltoid, but at least the developmental 

 phenomena do not favour the converse hypothesis. 



The second species occurred, as above mentioned, in one case alone, 

 in two other localities together with Phjcopeltis expansa. 



In both instances the thallus presents all the main characters of 

 the Phyllactidium tropicum of Mobius, but all specimens appear black 

 by refiected light, and a dark blackish-green by transmitted light. 

 The colour is entirely different from that of all species of Cephaleuros 

 and Phycopeltis, and resembles that of many fungi. 



It is similarly different from all the filamentous Trentepohliace^, 

 except the doubtful T. elenea, which, with its lichen form Cystocoleus, 

 has so often been rejected by the authorities on fungi, and again 

 denied a place among the algae. 



In the present case it would be impossible to class the cellular 

 plate-like thallus with the fungi, and if we regard it as a Phycopeltis 

 there may be no reason why T. elenea should not also be restored 

 to a parallel position among the filamentous algal forms. 



The commonly observed interchange of green and yellow in other 

 members of the Trentepohliaceae, according to conditions of light and 

 moisture, is an entirely different phenomenon, as the green in that 

 case is a chlorophyll green, not the dark colouring of the black 

 moulds. 



The colour in this instance is no question of desiccation or de, 

 as the organism is in active growth ; neither have the atmospheric 

 conditions anything to do with it, as the plants are on the same 

 leaves as the bright yellow Phycopeltis expansa. 



K.I.A. PEOC, SEE. in., VOL. in. 3 B 



