OLFACTORY ORGANS OF LEPIDOPTERA 39 



to the smaller number of pores on the wings of butterflies, and 

 chiefly to the smaller number on their hind wings. The preced- 

 ing conclusion was derived from the following data: The total 

 number of pores on the legs of moths vary from 71 to 240, with 



140 as an average; on the legs of butterflies from 73 to 196, with 



141 as an average; on the front wings of moths from 52 to 662, 

 with 399 as an average; on the front wdngs of butterflies from 

 206 to 404, wdth 303 as an average; on the hind wings of moths 

 from 45 to 663, with 382 as an average; on the hind wings of 

 butterflies from 130 to 228, with 197 as an average; on the 

 mouth parts of moths from to 59, and on the same appendages 

 of butterflies from to 34. The total number of pores on moths 

 vary from 222 to 1422, with 930 as an average; and on butter- 

 flies from 514 to 784, with 645 as an average. 



As a general rule, all the other insects hitherto examined for 

 olfactory pores by the writer show^ed that the larger the species 

 the greater was its total number of pores. Relative to Lepidop- 

 tera this ruling is not true, because the larger species have 

 about the same number of pores as have the smaller species 

 (table 1, p. 43). 



The other variations, most of which are small, pertain chiefly 

 to the distribution of the olfactory pores. For sake of brevity, 

 instead of using the long scientific names of the Lepidoptera ex- 

 amined, the species will be numbered from 1 to 43, and those 

 interested in associating the names of the species with the varia- 

 tions described may do so by referring to the names and num- 

 bers of the species in the table on page 43. 



No wdng was found devoid of olfactory pores, although they 

 are reduced in number on the rudimentary wings of the females 

 of Hemerocampa and Alsophila (nos. 10 and 16). These wangs 

 will be discussed under sexual variations on page 41. The 

 disposition of the pores on the wings of the other specimens is 

 more or less similar to that already described for Bombyx mori. 

 The number of groups of pores on a wing depends on how 

 closely the pores he to one another. At a given place on one 

 wing the pores may be scattered and therefore do not consti- 

 tute a group, wliile on another wing at the same place, the 



