308 Mr. E,. I. Pocock on Arachnida from 



dark streak in the middle and by two at the sides, one passing 

 along; each eye ; while the blotches along the body are sub- 

 rhomboidal and more or less clearly defined from each other. 



In the other species (0. Cookii) the groand-colour is much 

 more yellowish, the head is more irregularly mottled or 

 marbled, and the blotches on the body are much more variable, 

 being less distinctly defined and separated. Size for size, too, 

 the scales are less numerous than in the former species. 



In their general colouring both these snakes are very much 

 like the venomous labarria, and, in fact, are often mistaken 

 for it by colonists generally, the elongated anterior teeth being 

 confounded wuth true poison-fangs. 



Time after time the commoner species has been brought to 

 the Museum under the name of the venomous Crotaline snakes, 

 even the native Caribs being deceived by their appearance. 



They are both terrestrial and arboreal, and are most fre- 

 quently met with on the low stumps or the fallen trunks of 

 trees close to the riverside. In their movements they are 

 the most rapid of all the boas, and they seem to be much less 

 sluggish than their congeners. The commoner species has 

 frequently been kept in the Museum cages, but, without 

 exception, they have remained wild and untamed, if one may 

 use the expression — in marked contrast to the other boas, 

 which, under ordinary conditions, can be handled with 

 impunity. 



LI I. — On the Arachnida taken in the Transvaal and in 

 I^yasaland ly Mr. W. L. Distant and Dr. Percy Rendall. 

 13y R. I. Pocock . 



Order Scorpiones. 



Family Scorpionidae, 



Opisthophthahnus glahrifronSj Peters. 



Opisthoj}hthalvnis fflabrifrons, Peters, Mon. Berl. Ak. 1861, p. 514. 



Lac. Pretoria ( W. L. Distant). 



Hitherto not known from the Transvaal, but recorded from 

 Mashunaland, Kyasaland, and " Catfraria." 



Opisthoj)hthalmus pugnax^ Thor. 

 Opisthojyhthulmus puffiiax, Thor. Act. Soc. Itul. Sci. Nat. xix. p. 232. 

 Loc. Pretoria (IF. L. Distant). 



