326 



ABSTRACT OF PROCEEDINGS 



OF THE 



Royal Society of South Australia 



(Incorporated) 



FOR 1905-6. 



Ordinary Meeting, November 7, 1905. 



The President (J. C. Veico, M.D.. F.K.C.S.) in tiie 

 chair. 



Exhibits. — J. G. O. Teppek, F.L.S., a piece of rock from 

 near Paratoo, said to be a phosphate and nitrate of i^otassium 

 and iron. 



The President read a paper on the trapdoor spider of the 

 Adelaid-e Plains, of which the following is an abstract : — In- 

 terested in this remarkable animal from boyhood, Dr. Verc« 

 liad at various times taken pains to discover its habits. "The 

 burrow or nest of the female spider is a circular and nearly 

 vertical hole, lined for a short distance from the entrance 

 with silk webbing. The entrance is closed with a door con- 

 sisting of layers of webbing and earth, lined on the edges and 

 lower surface with silk weobmg. In plan the door is semi- 

 circular, and lightly bevelled on the lower side t-o fit exactly 

 the aperture, which is funnel-shaped. The hinge is formed 

 of webbing along the straight side, curved inwards a little 

 towards the ends, so preventing the door opening widely. 

 This modification of the hinge, together with the weight of 

 the door — the centre of gravity of which is always over the 

 opening — causes it to close automatically. Such a door must 

 afford considerable security against enemies: — (1) Is not 

 readily seen, being flush with the surrounding ground: (2) is 

 not easily opened ; (3) is well supported against outside pres- 

 sure." The President, having described the occupant, as fa.r 

 as necessary for a clear concej^tion of how it secures its nest 

 against an intruder, proceeded: — 'If the wall of our spider's 

 tube be carefully examined under a lens, a small area will be 

 found just below the bevelled edge, opposite the hin^e, which 

 is studded with pin-pricks, slightly elongated vertically. These 

 are made by the spines of the falces. The spider when alarmed 

 rushes to the door, fixes the two fangs into tlie door, and 



