118 
ZOOLOGICAL GEOGRAPHY. 
[PART III. 
may be claimed as exclusively Nearctic genera, on the ground 
that Guatemala was recently Nearctic ; and is now really a 
transition territory, of which the lowlands have been invaded and 
taken exclusive possession of by a 1ST eotropical 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 u 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 Pakearctic regions. This is undoubtedly the case 
if any fixed geographical boundary is taken ; and it would thus 
seem that the “Nearctic 3 ’ 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 list 
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. Sicilia 
4. Chamasa 
5. Catherpes 
6. Salpindus 
7. Psaltriparus 
8. Auriparus 
9. Gymnokitta 
10. Picieorvus 
11. Mniotilta. 
12. Oporoi'nis 
13. Ideria 
14. Relmintherus 
15. Helminthophaga 
16. Myiodioctes 
17. Phcenopepla 
18. Xanthocephalus 
19. Scolecophagus 
20. Pipilo 
21. Juneo 
22. Meloqnza 
23. Spizella 
24. Passerculus 
25. Pocecetcs 
26. Ammodromus 
27. Cyanospiza 
28. Pyrrhuloxia 
29. Calamospim 
30. Chondestes 
31. Gentronyx 
32. Neocorys 
33. Empidias 
34. Spliyrapicus 
35. Hylatomus 
36. Trochilus 
37. Atthis 
38. Ectopistes 
39. Gentrocercus 
40. Pediocates 
41. Gupidonia 
? Ortyx 
42. Oreortyx 
43. Lophortyx 
44. Callipepla 
45. Cyrtonyx 
46. Meleagris 
47. 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 peculiar 
species in the ancient Neotropical land south of Nicaragua. But 
we have, besides these, a number of genera which we are accus- 
