466 



Fig. 425. Antithamnion Butlerise Collins, a and b. 

 parts of the thallus with glands, c, part of the thallus 

 near the base, (a, b, about 175:1; c, about 60:1.) 



the filaments the opposite branches are issued nearest the basal 

 (proximal) wall of the cells in a way similar to that found in Grif- 

 fithsia tennis (Fig 425 c) ; higher up in the thallus, on the other 

 hand, the branches issue always a little below the upper cross- 

 wall of the cells (Fig 425 a, b) 



In the basal part of the thallus some of the cells are naked 

 or bear only a single short ramulus, but soon each cell bears two 



opposite bran- 

 ches, which,when 

 the thallus rea- 

 ches its highest 



development, 

 first gradually 

 develop ramuli 

 from their lower 

 side and later 

 from their upper 

 side also. The 

 rachis of the pin- 

 na consists of 

 about 10 cells, the ramuli on the lower side seldom of more than 

 3 to 4 cells, those on the upperside of 2 to 3. The length of the 

 whole pinna is about 500 //. 



The uppermost cell in the rachis of the pinna3 is often trans- 

 formed into a gland-cell (Fig 425 b). This gland-cell is short and 

 broad with roundish summit and has the usual transparent, ho- 

 mogenous contents. Now and then, too, the end cell of the ramuli 

 are transformed into a gland-cell (Fig. 425 a). The specimens 

 found were sterile. 



Found once in shallow water near the shore. 



St. Croix: White Bay. 



Geogr. Distrib. : Jamaica, Barbadoes. 



102. Antithamnion antillanum B0rgs. 



103. spec. 



104. Crouania attenuata (Bonnem.) J. Ag. 



105. Spyridia filamentosa (Wulf.) Harv. 



After having finished my description of this plant (p. 233) 

 I have come across an antheridial plant. The antheridial stands 



