PDF - Wallace Online

ZOOLOGICAL GEOGRAPHY. [part III.
may be claimed as exclusively Nearctic genera, on the ground
that Guatemala was rece^ly Nearctic ; and is now really a
transition territory, of which the lowlands have been invaded and
taken exclusive possession of by a Neotropical fauna, while the
highlands are still (in part at least) occupied by Nearctic forms.
In his article on " Birds," in the new edition of the " Ency-
clopaedia Britannica " (now publishing), Professor Newton points
out, that the number of 'peculiar genera of Nearctic birds is
much less than in each of the various sub-divisions of the
Neotropical region ; and that the total number of genera is also
less, while the bulk of them are common either to the Neo-
tropical or Paloearctic regions. This is undoubtedly the case
if any fixed geographical boundary is taken ; and it would thus
seem that the " Nearctic " should, in birds, form a sub-region
only. But, if we define " Nearctic genera " as above indicated,
we find a considerable amount of speciality, as the following hst
will show. The names not italicised are those which are repre-
sented in Mexico or Guatemala by peculiar species :
List of Typical Nearctic Genera of Land Birds.
1. Oreoscoptes
2. Harporhynchus
3. Sialia
4. Chamcea
5. Caiherpes
6. Salpinctus
7. Psaltriparus
8. Auriparus
9. Gymnokitta
10. Ficicorvus
11. Mniotilta.
1 2. Oporornis
13. Icteria
14. Helmintherus
15. Helwinthophaga
16. Myiodioctes
17. Phcenopepla
18. Xanthocephalus
19. Scolecophagus
20. Pipilo
21. Jimco
22. Melaspiza
23. SpizeUa
24. Passerculus
25. Pocecetes
26. Ammodromus
27. Cyanospisa
28. Pyrrhuloxia
29. Calamospiza
30. Chondestes
31. Centronyx
32. Neocorys
—
33. Empidias
34. Sphyrapicus
35. Hylatomus
36. Trochilus
37. Atthis
38. Ectopistes
39. Centrocercus
40. PedioccBtes
41. Cnjndonia
1 Ortyx
42. Oreortyx
43. Lophortyx
44. Callipepla
45. Cyrtonyx
46. Meleagris
17. Micrathene
The above are all groups which are either wholly Nearctic or
typically so, but entering more or less into the debatable ground
of the Neotropical region; though none possess any pecuKar
species in the ancient Neotropical land south of Nicaragua. But
we have, besides these, a number of genera which we are accus-