| Similarity |
Wallace |
Darwin |
| natural history collecting in childhood |
plants & beetles |
beetles |
| different species separated by rivers |
monkeys, insects & birds in Amazon (Rio Negro) |
rheas in Patagonia (Rio Negro) |
| similar species across oceans |
trogons (S. America & Malay) |
mockingbirds, finches (American mainland & Galapagos) |
| species similarities & differences in archipelago |
cockatoos, bird-wing butterflies & others (Malay) |
tortoises, finches (Galapagos) |
| Malthus, On Population |
1846 reading |
1838 leisure reading |
