F. Børgesen: Rhodophyceæ of the Danish W. Indies. 375 



at St. Thomas and in the Herbarium of the Botanical Museum, 

 Copenhagen, some specimens, determined by J. Agardh, are 

 kept; they are collected by Ørsted near Christianssted at a depth 

 of about 5 meters. 



St. Croix: Coakley Bay. 



Geogr. Distrb.: The warmer Altantic coast of Europe, Mediter- 

 ranean Sea, West Indies, Mexico. 



4. Gracilaria caudata J. Ag. 



Agardh, J., Spec. Alg., vol. II, p. 598; Epicrisis, p. 420. 



The specimens referred to this species are, when dry, of a 

 corneous-cartilaginous consistence. The main branches are rami- 

 fied on all sides, upwards with shorter ramuh, the upper ends of 

 the branches being bare. 



From a transverse section the cells in the interior of the 

 filaments are seen to be nearly of the same size as those in Gr. 

 compressa, their diameter reaching a length of about 300 [i. But 

 their walls are thicker, and the cells decrease more evenly out- 

 wards and pass evenly into the rather 

 thick cortical layer (Fig. 363). 



As I have had no authentic speci- 

 mens at my disposal I do not feel con- 

 vinced that my determination is right. In 

 referring my specimens to this species I 

 rely on the cartilaginous consistence of 

 the thallus, only slightly collapsed when 

 dry, and upon the anatomical structure. 



Tetrasporic plants were found in the 

 month of February. 



It occurs in shallow water in more 

 sheltered places and in the open sea at 

 a depth of about 10 meters. 



St. Croix: The harbour of Christianssted 

 and Christianssted's Lagoon, Green Cay, off Frederikssted. According to 

 J. Agardh this species has previously been found at St. Croix. 



Geogr. Distrib.: West Indies, Mexico. 



5. Gracilaria cylindrica nov. spec. 

 Gracilaria Blodgetti Borgs., Some new or little known West Indian 

 Florideæ (Bot. Tidsskrift, vol. 30, 1909, p. 18). 



Fig. 363. Gracilaria 



caudata J. Ag. 

 Part of a transverse 

 section (About 60:1). 



