— 134 - 



On the basis of these facts, in agreement with Dr. Howe, 

 I have therefore no hesitation in considering the forms in question 

 as two well-separated species. 



The forms occuring in the Danish West Indies can be grouped 

 in this way: 



Halimeda Tuna (Ellis et Solander) Lamx. 



Lamouroux, Extrait d'un mémoire sur la classification des Polypiers 

 coralligènes non entièrement pierreux (Nouv. Bulletin Soc. Philom., Tome III, 

 Paris 1812, p. 112. Barton, The Genus Halimeda, p. 11. Gorallina Tuna 

 Ellis and Solander, Nat. Hist. Zoophytes, London 1786, p. Ill, tab. 20, fig. e. 



var. typica Barton 1. c. p. 13, pl. 1, fig. 1. 



Of this form I have only collected a few specimens in rather 

 deep water (5 fathoms) in open sea off White Bay on the south 

 side of St. Croix. 



var. platydisca (Decsne) Barton, 1. c. p. 14, pl. 1, fig. 2. 



The specimens referred to this form have rather thin but large 

 (up to 4V2 cm. broad), joints, they have when dried a whitish-green 

 colour and are less calcified than the var. typica. They occur often 

 fixed to shells, corals etc. lying on the bottom, but they are also 

 able to grow upon the loose bottom, fixing themselves by means 

 of rhizoids to coarser sand particles etc. 



Only found in the open sea in deep water (10—20 fathoms). 

 St. Thomas in the sea to the west of Water Island, St. Jan in 

 the sound between this island and St. Thomas off Crux Bay and 

 in the sea north of St. Jan off America Hill. 



Halimeda discoidea Decaisne. 



J. Decaisne, Sur les Gorallines (Ann. Sc. Nat. Sér. II, 18). M. A. Howe, 

 Phycological Studies III (Bull. Torr. Bot. Club, 34, 1907, p. 495). 



var. typica, Howe, 1. c. p. 495, pi. 25, figures 11—20; pi. 26. 



The specimens referred to this variety seem to agree rather 

 well with Howe's description and figures, being only somewhat 

 smaller. They were all found in moderately deep water (about 

 5 fathoms) in open sea off White Bay on the south side of 

 St. Croix. 



var platyloba n. var. Fig. 3. 



Different from var. typica by having broader (up to 40 cm. broad) 

 joints and, especially the younger ones, being only very little calci- 



