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



In the young parts of the thailus long unicellular hairs are 

 given off from a great number of the peripheral cells forming a 

 dense coating round the filaments (Fig. 362 a). These filaments 

 are cylindrical — subclavate, being a little thicker in the upper 

 end; they are about 200 M long and 6 — 7^ broad. They have very 

 thin walls and are filled with protoplasma in the upper end. 



In this plant tetrasporangia are the only known organs of 

 reproduction. They occur in the upper apices of the pinnules 

 which become swelled and conical in shape. They are formed 

 here in great numbers in the peripheral tissue. The tetrasporangia 

 are oblong, rather small, about 50 f-^ long and 27 f^ broad; they 

 are cruciately divided. 



In a recently pubhshed Hst of algæ from Bermuda, Howe*) 

 has replaced this plant in the genus Gelidium, and he bases his 

 opinion on the fact that Gelidium cartilagineiim^ which in several 

 respects shows likeness to the present species, is allowed to remain 

 in the genus. As pointed out by M™® Weber, it is especially the 

 non-existence of the hyphæ in the middle of the thallus and the 

 great resemblance of the stichidia of this genus to those of other 

 species of Gelidiopsis which makes it most natural to place our 

 plant in the genus Gelidiopsis. 



Tetrasporangia were found in specimens gathered in the months 

 of January and February. 



This plant has originally been described upon specimens 

 from St. Croix which Vahl received from Rector West, and these 

 specimens are still in the Botanical Museum, Copenhagen. 



It is a very common species at this island, growing upon 

 coral reefs etc. in shallow water. At St. Thomas and St. Jan 

 I have not gathered it with the exception of quite a small 

 fragment dredged in the sea near the east end of the first men- 

 tioned island. 



Geogr. Distrib. : Seems to occur in all warm seas. 



Subfam. 2. Gracilarieæ. 

 Gracilaria J. Ag. 



I regret to say that, in the determination of several of the 

 species of this polymorphic genus, I have not always arrived 



•) In N. L. Britton, Flora of Bermuda, New York 1918, p. 514. 



