i 



248 



Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



altogether absent, and the tissue consists then of roundish cells, 

 larger in the middle, smaller outwards. 



Some of the specimens were small, often only a few centi- 

 meters high. They often grow like low dense tufts, in which other 



smaller algæ find protection, 

 e. g., Polysiphonia jerulacea, 

 Ceramiuni etc. 



Other specimens (Fig. 

 237) are large, up to 15 cm 

 or even more; they are much 

 hke specimens in Maze & 

 Schramm's collection of algæ 

 from Guadeloupe and by 

 these referred to Laurencia 

 dendroidea. They have a 

 terete stem. The branches 

 issue on all sides, but with 

 some tendency to be oppo- 

 site or verticillate. The ra- 

 muH are nearly cylindrical 

 or somewhat clavate. 



A transverse section of 

 the older part of the thal- 

 lus shows a tissue consisting 

 of roundish cells of different 

 sizes, without any trace of 

 a central axis. In the young 

 parts of the thallus, on the 

 other hand, this is more 

 clearly visible. 



The tetrasporangia are 

 found in the summit of the 

 ramuli. 



The cystocarps are pla- 

 ced either upon the ramuh, 

 or upon the branches which bear the ramuli. They are ovate- 

 pyriform in shape, about 230// long and 110 fx broad. They open 

 by a large orifice measuring about 60 /i in diameter. 



var. gelatinosa (Desf.) J. Ag. 



J. Agardh, Spec. Alg., vol. II, n. Ill, p. 761; Epicrisis, p. 653. 



Fig. 237. Laurencia obtusa (Huds.) l^amour. 

 Part of the thallus (About 3:1). 



