scale wide), pale yellowish stripe that ran from the crown of the head to the tip of the tail. Generally, though, these are relatively dull-looking snakes, except for male specimens from highland East Africa and the Western Cape province of South Africa, that usually have a striking yellow-and-black color pattern. Puff adders have a form of olfactory crypsis which has been shown to make detecting them difficult for trained dogs and meerkats, both scent-based predators. The exact nature of this ability is not known, but is hypothesized to be related to a low metabolic rate, as well as relocation after shedding and defecating. Scalation The head has a less than triangular shape with a blunt and rounded snout. Still, the head is much wider than the neck. The rostral scale is small. The circumorbital ring consists of 10–16 scales. Across the top of the head, there are 7–11 interocular scales; three or four scales separate the suboculars and the supralabials. It has 12 to 17 supralabials and 13–17 sublabials. The first three or four sublabials contact the chin shields, of which only one pair exists. Often, two fangs are on each maxilla, and both can be functional. Midbody, the snake has 29–41 rows of dorsal scales. These are strongly keeled except for the outermost rows. The ventral scale count is 123–147, the subcaudals number 14–38. Females have no more than 24 subcaudals. The anal scale is single. Distribution and habitat This species may be the most common and widespread snake in Africa. It is found in most of sub-Saharan Africa south to the Cape of Good Hope, including southern Morocco, Mauritania, Senegal, Mali, southern Algeria, Guinea, Sierra Leone, Côte d'Ivoire, Ghana, Togo, Benin, Niger, Nigeria, Chad, Sudan, Cameroon, the Central African Republic, northern, eastern, and southern Democratic Republic of the Congo, Uganda, Kenya, Somalia, Rwanda, Burundi, Tanzania, Angola, Zambia, Malawi, Mozambique, Zimbabwe, Botswana, Namibia, and South Africa. It also occurs on the Arabian Peninsula, where it is found in southwestern Saudi Arabia and Yemen. It is found in all habitats except true deserts, rainforests, and (tropical) alpine habitats. It is most often associated with rocky grasslands. It is not found in rainforest areas, such as along the coast of West Africa and in Central Africa (i.e., central DR Congo); it is also absent from the Mediterranean coastal region of North Africa. On the Arabian Peninsula, it is found as far