In his article on "Birds," in the new edition of the "Encyclopædia 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 Neotropical or Palæarctic 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 list will show. The names not italicised are those which are represented in Mexico or Guatemala by peculiar species:-- LIST OF TYPICAL NEARCTIC GENERA OF LAND BIRDS. 1. _Oreoscoptes_ 2. _Harporhynchus_ 3. _Sialia_ 4. _Chamæa_ 5. _Catherpes_ 6. _Salpinctus_ 7. _Psaltriparus_ 8. _Auriparus_ 9. _Gymnokitta_ 10. _Picicorvus_ 11. _Mniotilta_ 12. _Oporornis_ 13. _Icteria_ 14. _Helmintherus_ 15. _Helminthophaga_ 16. _Myiodioctes_ 17. _Phænopepla_ 18. _Xanthocephalus_ 19. _Scolecophagus_ 20. Pipilo 21. Junco 22. _Melospiza_ 23. Spizella 24. _Passerculus_ 25. _Pooecetes_ 26. Ammodromus 27. _Cyanospiza_ 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. _Pediocætes_ 41. _Cupidonia_ ? 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 {119}accustomed to consider as typically European, or Palæarctic, having representatives in North America; although in many cases it would be more correct to say that they are Nearctic genera, represented in Europe, since America possesses more species than Europe or North Asia. The following is a list of genera which have as much right to be considered typically Nearctic as Palæarctic:-- 1. Regulus 2. Certhia 3. Sitta 4. Parus 5. Lophophanes 6. Lanius 7. Perisoreus 8. Pica 9. Corvus 10. _Ampelis_ 11. Loxia 12. Pinicola 13. Linota 14. _Passerelia_ 15. _Leucosticte_ 16. _Euspiza_ 17. _Plectrophanes_ 18. Tetrao 19. Lagopus 20. _Nyctala_ 21. _Archibuteo_ 22. Haliæetus