2 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
The third faunal complex is of southern origin and extends up- 
ward from Mexico through. the Mississippi Valley. The species are 
in general adapted to arid conditions, and present a contrast to the 
species of the Canadian fauna, which are adapted to conditions in 
which melted snow forms a prominent factor. This contrast is best 
shown in those species which depend upon temporary water. Species 
uddicted to permanent water are naturally more independent of con- 
ditions of moisture or aridity, and their distribution depends more 
upon temperature. Thus in America the tropical area from about 
latitude 385° south to 35° north is inhabited by Culex quinquefas- 
ciatus. North and south of 35°, respectively, Culex pipiens occurs, 
and the two are coexistent for only a small distance. These are spe- 
cies dependent upon permanent water, and their distribution is gov- 
erned by temperature conditions. On the other hand, Aédes punctor 
is dominant in the Canadian zone, and gives rise to derivative forms 
in the coastal region and California mountains, but it is not found at 
all outside of the forested area, the Aédes of the south belonging to 
wholly different groups. These are species depending upon tem- 
porary water, in the one case snow water, in the other case casual 
rains, and the adaptations are wholly different. Distribution here 
depends upon moisture, not temperature. 
The principal diseases conveyed by mosquitoes in the United 
States are malaria and yellow fever. The danger of the former is 
everywhere present, the disease being conveyed by at least three 
species of Anopheles, with somewhat different capacities of carriage. 
The latter is only dangerous in times of epidemic, happily becoming 
scarce. The mere presence of the carrying species, Aédes aegypti, 
is therefore not necessarily a subject for alarm. 
The nomenclature adopted is that indicated in our standard Ameri- 
can work.? Certain differences maintained by European writers will 
be mentioned. 
T heobaldia instead of Culiseta as here used. There exists an earlier 
T heobaldius, which is held by the European writers not to invalidate 
Theobaldia. It is pointed out that there is no rule to this effect. It 
seems to us, however, that this similarity is confusing, and it is de- 
sirable to have names as assistance to study rather than the reverse. 
The difference consists in a gender termination, which in the case of 
species is never considered a sufficient difference. 
Taeniorhynchus instead of Mansonia as here used. Lynch Arri- 
balzaga founded 7 aeniorhynchus on a species which he considered 
to be taeniorhynchus Wiedemann, but which has been shown to have 
been ¢/tzllans Walker, the former an Aédes, the latter a Mansonia. 
3 Howard, Dyar, and Knab, The Mosquitoes of North and Central America and the 
West Indies, 1912-1917. 
