This chapter constitutes the core of this Atlas. It provides an in-depth analysis of the morphology of the dorsal guard hairs across 93 genera, encompassing 168 species, from all families of mammals with viable wild populations in Canada. Purely domestic animals, such as cats and dogs, are excluded. Supported by hundreds of photographs taken from museum specimens, this chapter examines the colour, medulla, and cuticle of the hairs and provides concise descriptions to facilitate within-genera comparisons. It has taxonomical and biological implications. It is intended to serve as a practical tool and reference for future trichomorphological studies.