446 Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



Goniotrichum Humphreyi, described in Collins, Holden and 

 Setcjiell, Phycotheca Bor. -Am., No. 421 and in Collins, The 

 Algæ of Jamaica (Proc. Arner. Acad., vol. 37, 1901, p. 251). 



4. Erythrotrichia carnea (Dillw.) J. Ag. 



5. Erythrocladia subintegra Rosenv. 



6. Acrochætiiim Sargassi Børgs. 



7. — crassipes Børgs. 



8. — piilchollum Børgs. 



9. — netrocarpum Børgs. 



10. — gracile Børgs. 



11, — cæspitiforme nov. spec. 



Thallus parvus, gracillimus cæspitosus usque ad 700 /j- altus 

 in Padina Hoiceana epiphyticus. Pars basalis e filis repentibus 

 plus minus lateraliter confluentibus composita. Cellulæ sub- 

 breves, 8 fj. longæ et 5 7^ latæ. 



Fila erecta quoquoversum ramosa, ad apicem versus atte- 

 niiata; ramis sparsis nonnumquam secundatis aut irregulariter 

 ortis. Cellulis in inferiori parte filorum ca. 5 ft latis et 12 /i longis, 

 in superiori ca. 2,5^« latis; in ramis paulo minoribus, inferioribus 

 3 — 4 [i latis, superioribus ca. 2 /^ latis. 



Rami recti, sub angu^is acutis surgentes; in inferiori parte 

 eorum ramuli breves sporangia gereutes. 



Sporangia pedicellata aut raro sessilia, 11 — 12 // longa et 

 6 IX lata. 



Chromatophorum parietale irregulariter lobatum aut per- 

 foratum pyrenoide laterali munitum. 



Upon a young Padina Hoiveana an Acrochætiiim was found 

 which I think must be regarded as a new species (Fig. 416). It 

 comes, undoubtedly, in several respects rather near to the Acr. 

 gracile described above on p. 26, but differs from this species in 

 its ramification and in the deviating arrangement of the spor- 

 angia. 



The plant forms small roundish tufts formed by the densely 

 placed and very ramified filaments. It grows with preference 

 along the edges of the Padina and the basal filaments run along 

 it. The base (Fig. 416 a), in which the original spore is not visible, 

 consists of filaments creeping upon the surface of the host. These 

 filaments merge more or less together, forming an often large, 



