132 



Papers from, the Department of Marine Biology. 



well-grown bushes, occurs on both the east and west sides of the island, 

 but back some distance from the shore. The northern half of the key 

 is implanted rather thickly by two patches of Iva imbricata, separated 

 by a band of U7iiola. Near the middle of the island is a single small 

 group of Sccevola plants. Sesuvimn occurs on the north and northwest 

 shores. In a comparison with Lansing and Millspaugh's survey it is 

 seen that the plants listed are exactlj^ the same as those in the present 

 survey; 8 species are given, and these are the same with the exception 

 of Cakile fusiforviis, which is perhaps the same systematic error noted 

 before, C. lanceolata being the one noted on the island at present. 

 Taking these facts as evidence, one may assume that in the 12 years 

 gone by all the species have held their footing and some have increased 



+ 1. Cakile lanceolata. 



9 2. Chamaesyce buxifolia. 



Jk. 3. Cenchnis incertus. 



iK 4. Iva imbricata. 



O ,5. Scaevola plumieri. 



A 6. Sesuvium poitulacastrum. 



T 7. Toumefortia gnaphalodes. 



ai£ 8. Uniola paniculata. 



East Key. Two inclies= one-fifth statute mile. 



in amount, but not at the expense of the others, and as this key is very 

 rarely visited, the ecologic influences governing the distribution of the 

 species have been undisturbed. 



SPECIAL ECOLOGY. 



Seasonal differences. — As might be expected from the data presented 

 under ''climate," the conditions are fairly uniform. The general 

 appearance of the islands is the same at all seasons of the year. Of 

 course during the winter months and early spring, after the heavy 

 rains in September to December, there is more green carpeting in dry 

 places, due to various grasses and low herbs which turn brown and dry 

 in the later and hotter summer months, and such tropical trees as the 



