F. Borgesen : Phæophyceæ of the Danish W. Indies. 61 



and partly from the cells above the midrib. The rhizoids consist 

 of cylindrical cells 6 — 8 times as long as their own diameter and 

 end with a small irregularly lobed disc. These rhizoids can grow 

 out from any parts of the thallus which come near to the 

 substratum. 



Only sterile plants were collected. They were gathered in 

 shallow water and in a sheltered place. 



St. Croix: Lime Tree Bay. 



Geogr. Distrib. The West Indies, Mexico, Brazil etc. 



2. Dictyopteris plagiogramma (Mont.) Vickers. 



Vickers, A., Liste des Algues de la Barbade (Ann. sc. nat., Bot., 

 9e sér., t. I, 1905, p. 58) ; Phycologia Barbadensis, part. II, pi. IV. 



Haliseris plagiogramma Montagne, Centurie de plantes cell. exot. nouv. 

 (Ann. se. nat., Bot., 2e sér., t. 8, 1837, p. 356). 



In a collection of algæ which were sent me by Mr. 0. Han- 

 sen Ganneskov I found a single specimen of this beautiful plant. 

 It was provided with tetrasporangia. These occur in small groups 

 2 — 3 together which often coalesce into larger ones. They are 

 found in the middle of the frond and form a broad row placed 

 on both sides of the midrib. 



The plant was gathered at the shore of St. Croix. 



Geogr. Distrib. West Indies, Brazil, Pacific Ocean, Australia. 



3. Dictyopteris Justii Lamx. 



Lamouroux in Journ. Philom., 1809, no. 20, tab. 6, fig. A. Vickers, A., 

 Phycologia Barbadensis, part II, pi. V. 



Haliseris Justii C. Agardh, Species Alg., vol. I, p. 142. J. Agardh, 

 Species Algarum, vol I, p. 118. 



The specimen collected is so small that a certain determina- 

 tion is impossible. 



It was dredged in deep water about 20 meters in the Sound between 

 St. Thomas and St. Jan: off Cruz Bay. 

 Geogr. Distrib. West Indies. 



Fam. 2. Fucaceæ. 

 Turbinaria Lamx. 



1. Turbinaria trialata Kiitz. 



Kützing, Tab. Phycol., vol. X, 1860, p. 24, tab. 67. Barton, E. S., 

 A systematic and structural account of the genus Turbinaria Lamx. 

 (Transact. Linn. Soc. of London, 2. Ser., Bot., vol. Ill, 1891, p. 218). 



