1 88 E. JACOBSON, THOMISUS DECIPIENS KORBES. 



had the kindness to identify the specimen, which is now 

 placed in the Leyden Museum of Natural History. 



The specimen caught in Java was certainly of a different 

 species, its colour being of a much darker brown. Also there 

 was no trace of a web on the leaf. I do not know whether 

 this spider too gave off some peculiar odor, the idea dit 

 not occur to me then, but I am convinced now that this 

 must have been the case and I feel sure, that all the species 

 of spiders said to imitate birds' excrement are giving off 

 some attractive smell, otherwise it would be quite uncom- 

 prehensible how the}' could manage to catch their prey. 

 As they do not construct an}- webs in order to catch insects, 

 and do not roam about to leap upon their victims, as other 

 Attidae are wont to do, but remain nearly motionless on 

 the same spot, often for a ven' prolonged period, they must 

 possess some other means to attract their prey. 



Entomologists should direct their attention to this point, 

 to ascertain whether all the other members of the excrement- 

 mimicing group of spiders, occurring in other parts of the 

 globe, have the same gift of attracting flies by a peculiar odor. 



A few months ago I heard that my friend Dr. W. DOCTERS 

 VAN LEEUWEN, the Director of the Botanical Gardens at 

 Buitenzorg (Java), being acquainted with my observation 

 described above 1 ), was able to confirm the fact from his 

 own observation of a spider that he discovered in the grounds 

 of the Botanical Gardens. 



The experiences relating to this case are following below. 



Fort de Koek, Oct. 1920. Eduard Jacobson. 



The mimetic spider, a Thomisid, figured on plate 12, fig. 4, 

 was found on the 30 th of March 1920 by Dr. DOCTERS VAN 

 LEEUWEN at the Botanical Gardens, Buitenzorg, resting on 

 a leaf of a Liliacea. According to Mr. HOGG it must be a 

 variety of Thomisus decipiens FORBES, from Sumatra. 



The spider, in appearance, very much resembles excrements 



*) A preliminary account was given by me in the periodical ,,De 

 Tropische Natuur" 1919, p. 18. 



