106 

 Halimeda Lamour. 



1. Halimeda Tuna (EJlis et Solander) Lamx. 



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

 coralligenes non entierement pierreux (Nouv. Bulletin Soc. Philom. Tome III, 

 Paris 1812, p. 112). Barton, The Genus Halimeda (Siboga Expeditie, Mo- 

 nogr. LX, 1901, p. 11). Howe, Phycological Studies III (Bull. Torrey Bot. 

 Club, vol. 34, 1907, p. 494). Borgesen in Bot. Tidsskrift, vol. 31, 1911, 

 p. 134. 



Corallina Tuna Ellis and Solander, Nat. Hist. Zoophytes, London 

 1786, p. Ill, tab. 20, fig. c. 



var. typica Barton 1. c. p. 13, jdL 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, pi. 1, lig. 2. 



The specimens referred to this form have rather thin hut 

 large (up to 4^4 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 them- 

 selves 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 Cruz Bay and in the 

 sea north of St. Jan off America Hill. 



Geogr. Distrib. Found in nearly all warm seas. 



2. Halimeda discoidea Decaisne. 



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

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

 sen, 1. c, p. 134. 



As pointed out in my above quoted paper I agree with Howe 

 in considering H. discoidea as well separated from Halimeda Tuna. 



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. 



