NOTK OX THE (KCCkRKNCE OF A IMCDAE N()S1<: iN 

 THE MALI-: OF A TRAP-DOOR SPIDICR (STASIMOPUS) 



B\ John Hewitt, B.A. 



It has 1(111,2^ ])eon known that spiders arc sensitive to tKlours 

 of various kinds. This can be verified in most species by the 

 simple experiment of hokhns: a scented rod near to the spider, 

 away from her hne of vision and without actually touchin,CT her, 

 when the creature will shew an appropriate response according 

 to the nature of the scent em])loyed: she may either ap])roach 

 the rod with apparent pleasure, or more often may withdraw 

 therefrom with more or less distinct signs of dissatisfaction. 



The position of the organ of smell is not known. Some 

 .writers have supposed that the olfactory sense resides in the 

 palps, and others seem to have suspected the chelicer^e ; how- 

 .ever, it was clearly shewn by the Peckhams (1) that spiders 

 bereft of their palps can still smell perfectly well. The most 

 recent writer on the subject. 13r. N. E. MTndoo (2) after sum- 

 marising all the previously published data relating thereto, and 

 submitting the results of his own experiments, concludes that the 

 olfactory sense is subserved by the lyriform organs which occur 

 in all spiders on most of the joints of the legs and of the palps, 

 and often also on the chelicene. spinners, sternum and cara}3ace. 

 These lyriform organs certainly have the essential structure of 

 a sense organ, and in one species (a Lyosa), MTndoo shews 

 that, on carefully varnishing the surface of all the lyriform 

 organs with vaseline, the sj)ider's sensitiveness to odours becomes 

 very greatly reduced. 



So far as I can ascertain, no c^ne has hitherto observed any 

 Avell-defined localisation of the (~il factory sense in spiders. There 

 is a hint of it. ])erhaps. in a ])aper, which I have not seen, by 

 McCook, who a]:)])arenth- interprets the exi^eriments of the 

 Peckhams as indicating that the olfactory sense organs are dis- 

 tributed more or less over the entire surface of the body, espec- 

 ially at the tips of the feet and at the a])ex of the abdomen. 

 Recently I have had the op])ortunity of experimenting with 

 some adult males of a common trapdoor si>ider. Stasiinof^iis s]).. 

 kindly collected for me at Alicedale by Air. Frank Cruden dur- 

 ing the months of April and May. I may mention that the 

 males of trapdoor spiders are very rare in collections, and 

 nothing has been written on their habits; yet the fact that these 

 creatures are structurally amongst the most primitive of living 

 spiders should lend a special interest to the study of their be- 

 haviour in life, particularly in connection with courtship and 

 mating, which, in manv two lunged sj^iders, is extraordinarily 

 complex. 



The specimens examined were of moderately large size, and 

 when at rest their long slender legs were often extended away 

 from the body, which was very convenient when experimenting 

 on the localisation of sense organs. Thev were comparatively 



