268 W. WESCHE. 



in the walls of the palpi (Fig. 14). Unfortunately I have no- 

 preparation of the male of this species, but I find a similar struc- 

 ture in the male of R. punctatus, though smaller in size and with 

 a shorter duct; as also in a Tasmanian species as well developed 

 as in the former species. The differences between these two- 

 species in this respect are so marked that it is possible to separate 

 them on this character alone (Fig. 13). 



The uses of the organ are obscure, but they are probably similar 

 in both the myriopod and the insects. The poison duct in the 

 legs is quite similar to that part in the maxilla; it traverses many 

 joints and opens underneath the claw between two bristles 

 inserted at its base. Without a doubt it is the homologue of 

 the duct which moistens the pulvilli in the flies. Again referring 

 to the maxillary gland, my observations have not ended here, 

 as the palpi of Simulium reptans 9 and 5. ornatum cf 1 have 

 similar structures, though they communicate with the air by a 

 different opening. Moreover in the mouth of two British species 

 of Cryptops, on the maxillae, or more properly speaking the 

 maxillipeds, and absolutely homologous in situation and structure, 

 are similar glands to those found in the Indian Scutigera. 1 



That this structure should be found surviving in Diptera is 

 exceedingly remarkable, but not more so than the fact that the 

 duct which leads the poison to the many claws of Scoliopendra 

 should be found in a precisely similar condition in nearly all 

 insects. I have found it throughout Diptera, in Blatta, Forficula, 



t 



Panorpa, Lepidoptera, Hemiptera, in fact in all insects where 

 there are membranes on the claws that need irrigation. 



I have studied the sense organs of insects for many years, and 

 by comparing the large number of preparations, using modern 

 optical methods and objectives I have become familiar with 

 their appearance in the antennae, palpi and mouths of Diptera,. 

 and many other insects. Unless I am greatly mistaken, and 

 mistakes are easily made in such minute structures, I can say 

 with confidence that there are found in the palpi of Rhyphus and 

 Simulium homologous organs of peculiar structure; and judging 

 from a comparison with Scutigera, this character is one of the 



1 I find the structure in a modified form in a small Lithobius, found in a garden 

 in London. 



