NOTES. 575 



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 mark- 

 ings, aud 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 (Protoptertts) is one of the Double-breathers or 

 Dipnoi, a member of a small class between Fishes and Amphibians, repre- 

 sented 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 Urdus. 



The Uraus snake or Aspis is the well-known Egyptian jugglers' snake 

 (Naja haje). It may be over six feet in length, and is very deadly. 



Note 46, p. 185. Spitting poison. 



The poison of a snake is contained in the secretion of a specialized 

 salivary gland. The compression of this venom gland propels the fluid 

 along a duct which leads to the groove or canal of the fang. Infection 

 with the venom only occurs when, by more or less of a bite, the poison is 

 injected into the victim. No spitting of poison is known, nor would it 

 have effect without a wound. 



Note 47, p. 186. The Gecko. 



Figures and a brief description of the gecko's clinging foot will be found 

 in Semper's well-known Animal Life (International Science Series, 

 1881). The clinging power is due to numerous long bristle-like hairs on 

 the sole of the foot. These appear to be modifications of the " casting- 

 hairs " which are used in " skin-casting ". 



