Summer-sleep in torrid regions, affecting a few fishes, amphibians, and reptiles, is a phenomenon analogous to hibernation elsewhere, but its physiological explanation is even more obscure.
[Note 41] p. 174.—The Karroo.
Karroo, a general name for the highland steppes of South Africa. See H. A. Bryden’s Kloof and Karroo (1889).
[Note 42] p. 178.—Cerastes (Vipera hasselquistii).
The horned viper is the most common viper of Northern Africa. It is extremely poisonous. It is of a brownish-white colour with darker markings, and has a scaly spine or horn over each eye. This species is usually supposed to have been Cleopatra’s asp.
[Note 43] p. 182. See Note 39.
[Note 44] p. 183.—The mud-fish.
This remarkable animal (Protopterus) is one of the Double-breathers or Dipnoi, a member of a small class between Fishes and Amphibians, represented by three genera—Ceratodus in Queensland, Lepidosiren in Brazil, and this Protopterus in Africa. They differ in many ways from other fishes, being physiologically intermediate between Fishes and Amphibians. Hundreds of specimens have been brought within their ‘nests’ from Africa to Europe. Brehm speaks of the complete enclosure of the capsule, but this is now known to communicate with the outer world by a tubular passage through the mud. At the foot of this tube the mud-fish keeps his nostrils. The lung is a specialization of the swim-bladder which is present in most fishes.
[Note 45] p. 184.—The Royal Aspis or Uräus.
The Uräus snake or Aspis is the well-known Egyptian jugglers’ snake (Naja haje). It may be over six feet in length, and is very deadly.