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



383 



The plant (Fig. 367) is characterized by the small, stellate, 

 spiny branchlets found scattered upon the filaments. They have 

 3 — 5 rays and are peltately fixed to the branches. Tendrils are 

 now and then present, but not upon all specimens. The plant 

 forms rather large, richly ramified bushes up to about 20 cm high. 



A transverse section (Fig. 368) 

 of the thallus shows rather large 

 cells in the middle, smaller to- 

 wards the periphery. The cortical 

 layer consists of a single layer of 

 cells which have a very thick 

 cuticula often 25 — 30 ^ thick. A 

 longitudinal section shows that the 

 cells in the middle are about 

 3 — 4 times longer than broad. 



The Acrochætium Hypneæ des- 

 cribed on page 51 of this volume is 

 found upon this plant in whose 

 thick cuticula its basal part is 

 immersed. 



This species has been found a few times in sheltered places 

 in shallow water. 



St. Thomas: in the harbour of Charlotte Amalia; St. Croix: near 

 Christianssted. Ørsted has gathered it as St. Thomas. 

 Geogr. Distrib.: West Indies, Guinea, Japan etc 



Fig. 368. Hypnea cornuta 



(Lamour.) J. Ag. 



Transverse section of the thallus. 



(About 100:1). 



3. Hypnea cervicornis J. Ag. 



J. Agardh, Spec. Alg., vol. II, p. 451; Epicrisis, p. 546. 

 Hypnea spinella Kütz., Tab. Phycolog., vol. 18, tab. 26. 



The specimens referred to this species form roundish bushes 

 composed of numerous, much branched filaments. No main bran- 

 ches are present, all the branches being of nearly the same size 

 and mostly rather thin. The ramification is very irregular, the 

 branchlets longer or shorter with acute apices. Frequently the 

 upper ends of the filaments get an antler-like appearance being 

 often curved and their branchlets decreasing in length towards 

 the top. 



Some of my specimens might perhaps quite as well be re- 

 ferred to Hypnea divaricata Grev. of which some specimens from 



