280 



My specimens agree in the main with the Mexican plant, 

 only they are much more vigorously and robustly developed. The 

 Mexican plant has more slender filaments and, moreover a taller 

 thallus than mine, and agrees better with HARVEY'S figure (1. c.). 



Fig. 279. Polysifthonia ferulacea Suhr, J. Ag. 

 Summit of a plant with antheridial stands. (About 125:1). 



That the specimens collected by me are so robustly developed 

 is most probably due to the exposed places in which they grew. 

 Thus they were found upon the coral reef connecting the Hurri- 

 cane Island with St. Thomas, a locality, and the peculiar algal 

 vegetation of which I have mentioned earlier*). P. ferulacea forms 

 here, together with Caulerpa racemosa, L reducta, Cladophoropsis 

 membranacea and a few other alga?, low, compact patches which 

 are all the more strongly felted together inasmuch as most of these 

 algse occurring here are able to develop haptera from nearly every 



*) B0RGESEN, F., An ecological and systematic account of the Caulerpas 

 of the Danish West Indies (Kgl. danske Vidensk. Selsk. Skrifter, 7. Rk. 

 Naturv.-Mathem. Afd. IV, 5, 1907, p. 346). 



