264 TROPICAL MEDICINE AND HYGIENE 



and prehensile, and the prevailing colour is greenish ; 

 the lateral scales are smaller than the dorsals and are 

 more or less oblique, but their keels are not serrated ; 

 the ventral shields are not ridged, and the sub-caudals 

 are in a single row. The species, two or three in number, 

 are found in forest, from Liberia to German East Africa. 



(/) Causus (fig. 104, e). In this genus the head, like that 

 of a harmless Colubrine, is oval and is covered with large 

 symmetrical shields, and there is a loreal shield ; the 

 pupil is round, and the eye is separated from the labials 

 by small sub-orbital shields. The species are found all 

 over the southern part of Africa, from Sierra Leone and 

 Uganda to the Cape. Causus rhombeatus is the commonest 

 and most widely ranging species. Its colour is variable, 

 olive or slaty-brown, either uniform, or, more usually, 

 with a dorsal series of large dark spots or V-shaped 

 bands, and there is commonly a dark V-shaped mark 

 on the crown. Dr. H. E. Arbuckle was the first to 

 observe that its poison-glands are band-shaped, entirely 

 subcutaneous, and about one-fourth the entire length 

 of the animal. He also describes its venom as pro- 

 ducing locally great ecchymosis and discoloration, and, 

 constitutionally, drowsiness, muscular weakness, and 

 haemolysis. 



(g) Atracaspis (fig. 107). In this also the head is, like 

 that of many Colubrines, not distinct from the neck 

 and covered with large symmetrical shields, but there 

 is no loreal; the eye is minute, and the pupil round, 

 and the third and fourth upper labial shields are usually 

 in contact with the eye. The dentition is peculiar ; 

 besides the poison-fangs there are very few teeth at all 

 in the mouth. The numerous species are commonly of 

 a blackish colour aud are found all over the southern 

 part of Africa, from Cape Verde and Sornaliland to Cape 

 Colony ; two species occur outside Africa, namely, one 

 in Arabia and one in Persia. 



THE THANATOPHIDIA OF AMERICA number about 

 seventy species. Except for the widely distributed sea- 



