226 



Subfam. 5. Crouanieae. 



\ 



Antithamnion Nagl. 



1. Antithamnion antillanum nov. spec. 



Fronde caespitosa, fills repentibus decumbentibusque, sub- 

 strato adfixis, fills erectiusculis ramulis oppositis instructis. 



Ramuli alterne pinnati, pinnis pinnulas singulas (raro plures) 

 in exterior! latere gerentibus ; pinnulis plerumque ex binis-quaternis 



(raro pluribus) cellulis compositis, in 

 superior! (interiori) latere glandula 

 ovata instructis. 



Tetrasporangia cruciatim divisa, 

 e cellula basali pinnularum orta. 



The base of the plant consists of 

 decumbent, creeping filaments, from 

 which the erect filaments arise; often, 

 too, the ends of these filaments grow 

 upwards. The creeping filaments are 

 fastened to the host plant by means 

 of vigorous haptera (Fig. 213). The 

 stalk of the hapteron is of variable 

 length, often moniliform, the cells 

 being oval of shape. They have thick 

 walls ; their length varies between 35 

 65 fj. or more, their breadth is about 

 2025/7. The stalk ends in a flat, 

 disk, consisting of coherent rhizoids. 



The erect filaments Fig. 214 are 

 oppositely and distichously ramified 

 and bear two kind of branches: some 

 of them growing out as main stems 

 like themselves, the others as short 

 branchlets with limited growth. 



The cells in the main stem are 

 nearly cylindrical, of variable size from 

 70200 n long and about 40 50 ^ 

 broad. 



Fig. 213. Antithamnion antilla- Th branchlets (Fig. 2 15) are alternat- 



num nov. spec. Part of a de- ' . 



cumbent filament from which mgly ramified, the pinna? being placed 



downwards rhizoids, upwards distichously along both sides of the 

 branchlets are issued. J 



(About 85:1). rachis. 



