328 S. W. WILLISTON. 



Gynoplistia, another tipulid genus, from Australia, New Zealand, 

 New Guinea and Celebes, with numerous species, has from six- 

 teen to twenty antennal joints, branched like those of Cerozodia. 

 Are these forms really survivals of primitive types ? I do not 

 think that we are permitted to doubt it. Their habitats and dis- 

 tribution alone indicate that, and the fact that three of the few 

 known forms of diptera with multiarticulate antennae are known 

 only from the Miocene is also corroborative. Magachile, per- 

 haps identical with Protoplasa, is one of these amber forms. 



Among the Cecidomyidae we have a few forms with multi- 

 articulate antennae, as many as thirty-six in the males of some 

 Hormomyia with a maximum of twenty-four in the females. The 

 only other forms with abnormal multiarticulate antennae that I 

 can discover in the literature, are Rhachicerus, with from twenty 

 to thirty joints, Chrysthemis, an amber genus with twenty-three 

 joints ; and Electra, also from the amber, with thirteen joints, all 

 belonging to the xylophagid " Brachycera," having a normal 

 maximum number of ten joints. The fact that some of these 

 examples have a larger number of joints in the male antenna 

 than in the female, may seem to indicate that the increased num- 

 ber is an acquired secondary sexual character, and that the female 

 antenna is nearer the primitive number. But, why may we not 

 assume that the diminished number in the female is the real ac- 

 quired sexual character, and not the increased number in the 

 male ? Certainly this must be the case with such forms as Tany- 

 pus and its allies among the Chironomidae, Micromyza and others 

 of the Cecidomyidae. From the frequent occurrence of sexual 

 variation in these apparently primitive forms, I think it is prob- 

 able that the early diptera all had fewer antennal joints in the 

 females than in the males. I am confident that we are safe in 

 accepting at least thirty-nine as the original and primitive anten- 

 nal number among diptera ; safe in the belief that the evolution 

 of the dipterous antenna has always been by reduction from this 

 primitive number, and never by the reacquirement of joints once 

 lost. 



Just how the loss of antennal joints has occurred is not always 

 clear. It may be assumed that it has been by the loss of distal 

 segments, but this is certainly not always the case, especially when 



