404 William Russel Dudley 



Cretaceous of Europe, indeed prove these forms to be of very 

 ancient origin. Zostera is by far the best known genus and 

 is apparently one of the oldest types. It is the only genus of 

 the group which has species at all cosmopolitan in their dis- 

 tribution. One of these, Zostera marina, frequent in the old 

 world, extends to the shallow bays and tide-water coves of 

 Atlantic North America, and is the only sea-grass found in its 

 waters. The distinguished morphologist, in whose honor this 

 paper was written, will recall the submarine meadows of Zos- 

 tera along the New England coast as giving shelter to num- 

 erous forms of animal life. The wide extension of this species 

 and Zostera nana, an old-world form, so far as definitely 

 known, shows Zostera to be the most flexible and the strongest 

 of the old types believed to exist in the Tertiary seas. 



From this strain only one other subsidiary type of generic 

 importance — Phyllospadix, appears to have sprung and per- 

 sisted till recent times. This genus and Zostera are charac- 

 terized by a flattened spadix, closely invested by the spathe, 

 in which the flowers are entirely concealed until anthesis. 

 The monoecious spadices and ovoid fruits of Zostera are re- 

 placed in Phyllospadix by dioecious spathes and cordate- 

 sagittate fruits. The retinacula, or appendages protecting the 

 sexual organs, wanting in some Zosteras, small in others, are 

 strongly developed in Phyllospadix. 



Some years ago, while in Berlin, my attention was partic- 

 ularly called to the genus under consideration, while looking 

 over with Professor Ascherson the drawings for his mono- 

 graph of the order in the " Pflanzenfamilien." I was then 

 chiefly struck with the fact that the genus was a nearly mono- 

 typic one and peculiar in its geographical restriction. When 

 the plants were first seen growing along the bold shores of 

 Santa Cruz county, one was most impressed by the remarkable 

 departure from Zostera in habitat. Like manj' of the great 

 Algse, it is either a surf plant living on exposed rockj- points, 

 or grows in coves of rocks and sand, where the strong move- 

 ment of the waters keeps the long, supple leaves constantly 

 doubling upon themselves. 



As this paper concerns itself with themorpholog}^, anatomy 



