22 Dansk Botanisk Arkiv, Bd. 2. Nr. 2. 



Mitchell, 1. c, p. 56, the innerside of the strand in the netlike 

 thallus is often ruptured in such a way that a large area of the 

 cells in the interior of the thallus are exposed. The edges of 

 these fissures have an inclination to curl inwards. If it happens 

 that the edges come near each other the small surface cells 

 grow out into shorter or longer rhizoid-like prolongations and in 

 this way the fissure may be closed (comp. Fig. 13). 



This species is common on the shores of the Islands. It occurs in the 

 littoral and upper sublittoral region, in sheltered or not very much exposed 

 localities. 



Geogr. Distrib. Seems to occur in all warmer seas. 



Rosenvingea nov. gen. 1 ). 



Frons tubulosa, cylindracea, vel leviter compressa, disco 

 radicali adfixa, ramosa, ramis sparsis vel pseudodichotomis. In- 

 crementum intercalare divisione cellularum frondis totius adest. 

 Frons ex 3 — 4 stratis cellularum composita, cellulis exterioribus 

 minoribus ad cavitatem versus majoribus, cellulis peripheræ chro- 

 matophora disciformia singula continentibus. Pila aut singula aut 

 plura aggregata, per totam frondem sparsa aut in soris aut in 

 parte sterili præsentia. 



Sori maculis valde irregularibus per totam superficiem 

 frondis dispersi. 



Sporangia plurilocularia subcylindracea aut clavata, e cellula- 

 rum corticalium divisione orta. 



1. Rosenvingea Sanctæ Crucis nov. spec. 

 Frons cylindracea aut leviter compressa, ca. 20 cm alta, 

 superficie irregulariter rugosa, disco basali ex rhizoideis numero- 

 sissimis composito adfixa. 



Rami sparsi, interdum pseudodichotomi, ad apicem et inter- 

 dum ad basem attenuati. Pila aut singula, aut pauca aggregata 

 per totam superficiem frondis aut sterili, aut sporiferi sparsis. 

 Lat. pilorum = 8 — 9 p. 

 Sporangia plurilocularia, subcylindracea aut clavata, in soris 

 irregularibus per totam superficiem frondis distributa. 

 Long. spor. pluriloc. = 20 — 40 ix. 

 Lat, — — 5—12^. 



J ) Named after my compatriot, the well known phycologist, Dr. L. Kolde- 



RUP ROSENVINGE. 



