xviii Proceedings of the South African Philosophical Society. 



Mr. Orpen wrote that his brother, the kite Mr. F. H. Orpen, had 

 first told him that all the small dust columns which one sees over 

 the veld moved in the same direction as the cyclones in the Southern 

 Hemisphere, and his own observations confirmed this. Mr. Orpen 

 wanted to know if other members of the Society could also confirm 

 the observation. 



Mr. E. HuTCHiNS stated that he had noticed that the larger dust 

 storms moved clockwise over the Karoo, but he had seen small 

 ones turning in either direction. 



Mr. C. Stewart said that as the cause of the dust pillars was 

 purely local he saw no reason why they should turn in one direction 

 rather than the other. 



Mr. Garwood Alston thought the large and small ones must 

 move in the same direction. 



The President said that obviously there was room for further 

 data bearing on Mr. Orpen 's question being collected, and trusted 

 that some of the members would devote their attention to the 

 matter. 



Dr. W. F. PuRCELL gave some extracts from a paper on the South 

 African " Baviaan " and "Trap-door" spiders in the collection of 

 the South African Museum, and exhibited specimens of some of the 

 more interesting forms. 



The spiders may be recognised by their possessing four instead of 

 two lungs on the under side of the abdomen, and also by the fact 

 that their poison fangs are parallel and directed backwards, whereas 

 in other spiders the fangs are opposable. To the naturalist this 

 group is specially interesting, as it is generally held that the two- 

 lunged spiders were derived from four-lunged forms. In South 

 Africa the group is represented principally by two families. One 

 of these, the T her aphos idee, or " Baviaan " spiders, include our 

 largest spiders. Their feet are provided with a dense pad of short 

 hairs, which enable the animal to walk up perpendicular surfaces. 

 Five genera, two of which are new, and a number of species are 

 now known from South Africa. The principal genus is Harpactira, 

 H. atra being the well-known form from the Cape Peninsula. This 

 spider makes a hole in the ground, near the middle of which it 

 suspends its eggs on a thin web, and then sits at the bottom of the 

 hole. This arrangement serves to keep the eggs dry when water 

 gets into the hole. The Cape Town species is also recorded from 

 Gordon's Bay and from Malmesbury, but has not been found else- 

 where. Dr. Purcell exhibited other species, including II. tiyrina 

 from Port Elizal)eth and the Native Territories. 



Another group is the trap-door spiders proper, easily recognised 



