142 



The cells of this inferior part are filled with grams of starch, 

 yet they will die or dissolve little by little; it may also be that 

 the rhizines get some nourishment out of them. 



In sections I have often seen three layers of thalli one above 

 another. By these superposed thalli P. Nordstedtii approaches the 

 group of P. polystrata of which P. dura Heydr. is the type. The 

 name dura, given on account of the hard calcified nature of the 

 frond, is alone sufficient to show that our alga with its soft frond, 

 is a different species, not to speak of other differences, afforded 

 by the peculiar structure of the nemathecium of P. dura. 



I have seen only one nemathecium of P. Nordstedtii with 

 cruciate tetraspores, but it was still unripe. It had a height of 

 80//, and the paraphyses ended with a blunt cell; the cells were 



I l f 2 2 as long as 

 broad but this will 

 change with succeed- 

 ing growth. 



P. Nordstedtii ad- 

 heres totally and 

 firmly to the sub- 

 stratum. I cannot 

 say anything about 

 its colour for it was 

 preserved in alcohol 

 and 1 have seen no 

 dry specimens from 

 the W. Indies. 



The specimen from Nias that has so much in common with 

 the W. Indian one, has a pale pink colour. 



Found at St. Jan off Cruz Bay in a depth of about 12 fathoms. In 

 alcohol. (No. 1903). 



Subgenus 2. Eupeyssonnelia. 



5. Peyssonnelia (Eupeyssonnelia) simulans nov. spec. 



Thallus tenuis, orbicularis aut irregularis, substrate tomento 

 brevi adhserens sed facile a substrate solutus, durus, calcarius, 

 zonas concentricas et lineas radiales vix conspicuas exhibens, con- 

 stans hypothallo et perithallo. 



Hypothallus constat filis rectis, juxtappositis, cellula apicali 

 brevi, lata instructis. Cellula apicalis in sectione radiali altior filis 

 hypothalli. 



3QQDQQQ 



GOOQGEL 



Fig. 147. Peyssonnelia Nordstedtii nov. spec. Sec- 

 tion through part of nemathecium with cruciate 

 tetraspores. (250 : 1). 



