There are over 30 species of mimids in two larger and some ten small or monotypic genera. They tend toward dull grays and browns in their appearance, though a few are black or blue-gray, and many have red, yellow, or white irises. They range from 20 to 33 centimetres in length, and 36 to 56 grams in weight. Many mimids have a rather thrush-like pattern: brown above, pale with dark streaks or spots below. They tend to have longer tails than thrushes (or the bigger wrens, which they also resemble) and longer bills that in many species curve downward.