- 144 — 



common form and occurs in rather open and somewhat exposed 

 localities. It is found at St. Croix: on sandy shores behind Long 

 Reef and on the south side in Lime Tree Bay and White Bay; 

 further at Buck Island. 



forma cylindrica occurs in more sheltered localities with muddy 

 bottom; it is found at St. Croix near Krauses Lagoon. 



var. simulans (Howe). 



Halimeda simulans Howe, Phycological Studies III (Bullet. Torr. Bot. Club, 

 vol. 34, p. 491. 1907). 



This nice variety is a characteristic form with broad oval 

 joints; it possesses, when living, a nice, light-green colour. The 

 diameter of the peripheral utricles lies mostly between 35 — 54^; 

 but as mentioned above variations often occur. 



This form is found partly in the lagoons, growing in shallow 

 water upon the loose bottom, partly also in deep water down to 

 30 — 40 meters or more. 



St. Croix. Christianssteds Lagoon. Common in shallow water 

 upon soft muddy bottom; White Bay (10 meters of water). St. 

 Thomas, Bovoni Lagoon in shallow water; in the sea west of 

 Water Island in a depth of about 30 meters of water. 



Halimeda gracilis Harv. 



Harvey, Alg. Ceylon. No. 72. Barton, The genus Halimeda, p. 22. 



Of this nice species I have found a form in rather deep water 

 at St. Jan, which I think may be considered as new and for which 

 I propose the name: 



opuntioides n. var. 



Joints large, broadly suboval— reniform often distinctly crenu- 

 lated at the upper margin or sometimes even trilobed, having upon 

 the whole a very great resemblance to forms of Halimeda Opuntia. 

 The dried specimen is whitish-green in colour. The joints are ra- 

 ther thick but easily breakable, the calcification being not very 

 strong. 



Joints up to 14 mm broad and 9 mm high. 



Whilst its outer appearance is in this way rather different from 

 the two forms (f. typica and f. laxa) we find figured in Mrs. G e p p 7 s 

 monograph, the anatomical structure of our form agrees exactly 

 with the description and figures given by Mrs. Gepp. 



