I2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
marked that they are treated as geographic races only under present- 
day concepts, since 20 years ago they would have been considered 
distinct species. There are also several others that undoubtedly will 
be named later when further specimens corroborate differences now 
discernible in the few examples at hand. Thus of the 97 kinds among 
the tropical residents of the island more than 20 percent are distinct 
subspecies. Among these the most surprising is the race of the rusty 
spinetail (Cranioleuca vulpina), a species of South America not pre- 
viously found north of the valley of the Orinoco River in southern 
Venezuela and southeastern Colombia. It represents an avian ele- 
ment previously unknown in the avifauna of Central America. 
The differences that mark the resident races are mainly heavier, 
darker pigmentation, which may be explained in terms of more 
abundant rainfall, indicated by the considerable drainage system seen 
in the numerous rivers of the island. There is also a tendency in 
some to large bills, which is not unusual in isolated islands. 
The great forests that clothe Isla Coiba, still practically unbroken 
except for a relatively small area, offer habitat suitable for any of 
the birds that exist in such abundance as to kinds and individuals 
in the vast lowland area between southern México and northern 
Argentina. When we note those that are lacking in the island en- 
vironment, we find a matter for astonishment equal to that experi- 
enced with the amount of endemism among the kinds that do occur. 
The following list of families of birds of regular occurrence on the 
nearby mainland but not found on Coiba is noteworthy: 
Tinamous (Tinamidae) 
Curassows and guans (Cracidae) 
Trogons (Trogonidae) 
Motmots (Momotidae) 
Jacamars (Galbulidae) 
Puffbirds (Bucconidae) 
Toucans (Ramphastidae) 
Woodhewers (Dendrocolaptidae) 
In addition to these eight prominent families, there is no record 
of the wood-quails (Odontophorus), the long-tailed squirrel cuckoo 
(Piaya cayana), or the large forest woodpeckers (Dryocopus and 
Phloeoceastes). Ovenbirds (Furnaridae), except the rusty spinetail 
(Cranioleuca vulpina), are missing, as are antbirds, except the barred 
antshrike (Thamnophilus doliatus), manakins, except the lance-tailed 
manakin (Chiroxiphia lanceolata), many common genera of forest- 
loving tyrant flycatchers, wrens, except the house wren, and resident 
orioles and blackbirds, except the boat-tailed grackle. The common 
