North Africa 



INTRODUCTION 



Africa from the southern edge of the Sahara 

 nortliward is a vast region where tlie dominant 

 theme is heat and aridity. This is mitigated only 

 along the Mediterranean coast, in high mountains 

 such as the Atlas range, and along the great river 

 valleys and oases. 



The snake fauna contains few species partly 

 because of the rigors of the climate, and partly 

 because most of the desert is new and there has 

 been insufficient time for the evolution and spread 

 of a specialized desert snake fauna. The distri- 

 bution of snake species in northern Africa is not 

 well known. There are probably a number of 

 tropical African species that invade locally along 

 the large rivers in the southern part of the re- 

 gion. Only a few of the species are found pri- 

 marily in the desert; the majority occur around 

 zones of irrigation or natural water supply. 

 This increases the hazard of snakebite to the rural 



people ; however, the incidence of such accidents is 

 unknown. Egypt in the years 1944-48 reported 



Map 6. — Section ."«. Nortli .\frka. 



KEY TO GENERA 



1. A. Crown of head covered with small irregular scales; 



pupil of eye vertically elliptical 7 



B. Crown of head covered with large shields; pupil 



round or elliptical 2 



2. A. Loreal plate present 3 



B. Loreal plate absent 4 



3. A. Lateral scales rectangular and oblique; top of head 



with dark chevron marking (plate VIII, fig. 4) Causus rhombeatus 

 B. Without the above combination of characters NP* 



4. A. Eye very small, snout pointed, all subcaudals 



undivided Atractaspis 



B. Without the above combination of characters 5 



5. A. All dorsal scales smooth 6 



B. Posterior dorsal scales keeled; anal plate divided WaUerinnesia 



6. A. Scale rows at midbody more than 15 ; hood seen 



in life Naja 



B. Scale rows at midbody usually 1.'5; no hood Elupspidea 



T. A. Lateral scales oblique with serrated keels 8 



B. Lateral scales like dorsals 9 



8. A. Subcaudals single; ventrals not keeled Echis 



B. Subcaudals paired; ventrals keeled Cerastes 



9. A. Ventrals extending full width of belly 10 



B. Ventrals not extending full width of belly NP 



10. A. Body pattern of chevron-shaped crossbands; 



nostrils dorsal Bitis 



B. Body pattern not as above; nostrils lateral Vipera 



• NP = Nonpoisonous 



79 



