JOHNSTON: FLORA OF MARGARITA ISLAND. 281 
In connection with this discussion there is an interesting field for 
study in the distribution of the individual species of plants Avhether 
in groups or singly, whether in one place or scattered in many, and 
whether on one slope and not on another. 
The species of plants found on the seashore and by the lagoons are 
without exception growing in groups with but little intermixture. 
Almost any of the plants illustrate this, Rhizophora, Avicennia, Batis, 
Salicornia, and Trianthema. The species growing on the plains are 
found in abundance though well interspersed with other species. So 
far as was discovered Opuntia leptocaulis was growing in abundance 
but over only a small area to the west of Porlamar. Similarly, Croton 
Milleri was localized though well mixed with other plants. Many 
of the plants were to be found in different locations, which, however, 
had similar moisture conditions. This was even more accentuated 
in the valleys and hillside than on the plains. While many plants 
could be found in a fairly large quantity, the majority of the hillside 
plants occurred in small numbers. Some plants which were found 
only on the south slope of a hill might be found on the south slope of 
another hill but not on the north side. Further detailed exploration 
might tend to generalize this statement but the conditions as given were 
rather striking to me. For example, Steriphoma elliptica occurs on 
the south slope of South Hill and on the south slope of North Hill but 
not on the other parts of the island so far as explored. Bauhinia 
cumanensis occurs similarly. Cases of isolation are Securidaca only 
on the north side of North Hill, Hymenca Courbaril on the south side 
of South Hill and Pedilanthus on the summit of South Hill. 
The instances in which only two or three plants of a species were 
found are few and it must be admitted that a thorough examination 
of the hills and valleys in a better season would probably show more 
of the plants. Notwithstanding this the paucity of specimens was only 
too apparent to me when collecting, and it seems to be a fact that in the 
majority of cases (striking exceptions are Tribulus, Stachytarpheta, 
Jatropha, and Croton) the number of plants of the individual fepecies is 
very much smaller than is the case with our common plants of the United 
States. Only one plant was found of Chiococca micrantha, a half 
dozen near together of Securidaca, a single one of Hymenea, a single 
tree of Acacia macracantha in San Antonio valley and three or four 
along the river trail of El Valle, three plants of Oncidmm luridum, 
three of Huntleya, and three of Elleanthus attenuatus. The list 
