F. Borgesen: Phæophyceæ of the Danish W. Indies. 65 



The species was found on rocks close to , or a little above the 

 surface of the sea, in rather exposed or somewhat sheltered places. 



St. Croix: Green Cay, Coakley Bay, Long Reef. 



Geogr. Dis tri b. West Indies and warmer shores of America. 



4. Sargassum Hystrix J. Ag. 



J. Agardh, Nya Alger från Mexico (Öfversigt K. Vet. Akad. Forhandl. 

 1847); Spec. Alg., p. 322; Species Sargassorum Australia-, p. 91, tab. VII, 

 figs. 1 — 5. F. Børgesen, 1. c, p. 5. 



Carpacanthus spinulosus Kiitz., Tab. phycol., vol. XI, p. 15, tab. 46, fig. 2. 



As pointed out in my paper quoted above the two rather 

 damaged specimens found floating in the sea and referred to this 

 species closely resemble the figure of Carpacanthus sptnulosus of 

 Kützing. As characteristic of my specimens and as it seems 

 judging from his figure in accordance also with Kützing's, may 

 be pointed out (1) that the rather thin leaves have a strongly ser- 

 rated or dentated margin and many small cryptostomata spread over 

 the whole surface, (2) that the branched receptacles are provided 

 with acute processes along the margin; and (3) that the vesicles 

 are rather thin-walled. How far this form of Kützing's really 

 belongs to Sargassum Hystrix J. Ag. seems to me rather doubtful. 



In order to obtain clearer light in the matter I paid a visit 

 to Lund to compare my specimens with the original material 

 in J. Agardh's Herbarium. These latter agreed well with those 

 in the Herbarium of the Botanical Museum at Copenhagen, all 

 the specimens being collected by Liebmann at Campeche Banks. 

 From my specimens these plants differ in several respects. For 

 instance most of the different organs of the plant seem to be 

 smaller and markedly firmer and darker coloured ; the vesicles 

 are mostly somewhat smaller and have thicker walls, the leaves 

 are smaller but thicker and have only a few but larger crypto- 

 stomata though these may be often quite wanting. The recep- 

 stacles are shorter, but broader. I happened to come into corre- 

 spondence with Mr. A. Gepp concerning this question and asked 

 him if there was much material of Sargassum Hystrix in the 

 British Museum. In reply to my query he most kindly wrote: 

 — "As to your question about S. Hystrix, we have only one 

 trustworthy specimen of it ; and that I found some years ago 

 at the end of the genus and bearing these words : — "Carpacan- 

 thus — Kg. Ins. Ind. occ. Dan." [possibly issued by Hohenacker]. 

 It corresponds exactly with Kiitz., Tab. Phyc, XI, tab. 46, II. 

 So I placed it at once under Sarg. Hystrix. I noted on it : 



Dansk Botanisk Arkiv, Bd. 2. Nr. 2. 5 



