108
 

THE  NORTH AMERICAN  SPECIES  OF  DROSOPHILA.
 

XII. GEOGRAPHICAL DISTRIBUTION.

Table 9 shows the number of species of each genus of the Dro¬
sophilinse known from each of the main geographical regions. The
Polynesian region is considered separately, because the data now
available indicate that for this subfamily the fauna is more distinct
from that of the rest of the world than is the fauna of any other region.
This fact is probably due in large part to the incompleteness of the
data, for the word "Polynesian" in this case means practically "Hawai¬
ian Islands." The parts of the Oriental region nearest to these islands
have not been well explored. Australia and New Zealand have been
included in the Oriental region, again perhaps only because of a lack
of data. These islands are practically unknow^n, so far as their
drosophiline fauna is concerned. The same situation is found with
respect to the relation of Madagascar to the Ethiopian region.

Table 9 indicates that the Nearctic region is the poorest of all in the
number of species that it contains. The actual number recorded from
the Ethiopian region is somewhat less than that from the Nearctic,
but Africa has been very much less thoroughly collected than has the
Nearctic region. A discussion of each region in some detail follows
the table.

Table 9.—Number of species of each genus in each region.
 

Genus.
 

Nearct.
 

Neotr.
 

Palae.
 

Ethiop.
 

Orient.
 

Poly.
 

Total.
 


 


 


 

1
 


 


 


 

1
3
1
1
7

10
1

16

1

203

3

6

45
9
1
1

15
1

28
1
3
3
 


 


 


 


 

3
 


 


 

1
 

1
1
 

1
 


 


 


 


 


 


 


 

2
5
 

1
1
 

4
 


 

Chjanomyza..................
 

4
 

2

1

11
 


 


 


 

1
 

1
 

2

1

22
 

1
 


 


 


 

28
 

41
 

43
2
 

51
1
 

44
1
6
 


 


 


 


 


 

2
1
1
1
3
1
2
 

10
3
1
 

3
1
 

11
3
 

20
1
 


 


 


 


 


 


 


 


 

2
 

10
 


 

2
 


 


 


 

5
 

9
 

1
 

12
 

1
 


 


 


 

1
2
 


 

1
 

1
1
 


 


 

Total.......................
 


 


 


 

45
 

81
 

78
 

43
 

97
 

52
 

360
 

NEARCTIC  REGION.

This region is characterized by the presence of the two endemic
genera Pseudophortica and Sinophthalmus. It has a relatively large
number of species that also occur in other regions.    The five cos-