48 
Psyche 
[March 
in life I have examined dried specimens of T. alternans Loew and T. 
vespiforme (L.) and found the legs to be similarly marked. 
These observations show that in the Family Syrphidae there are 
at least four ways of achieving the appearance of aculeate antennae. 
These four ways represent at least three and perhaps four independent 
evolutionary innovations. Spilomyia and Sphecomyia certainly present 
evolutionary independent solutions to the problem of mimicking 
hymenopteran antennae. Ceriana and Tenthredomyia represent at 
least a third line and may have evolved solutions independently of 
each other. The antennae of both are stylate and otherwise similar. 
The antennae of Tenthredomyia are borne by a long process, but 
Ceriana exhibits a similar though very short process. Thus it is 
possible that these two genera present primitive and advanced ver- 
sions of the same evolutionary line rather than two separate lines. 
The question cannot be decided on the basis of the present evidence. 
Nicholson (1927) noted that among the Syrphidae long antennae 
are generally associated with those species in which the over-all 
mimetic resemblance to Hymenoptera is the most highly developed. 
My observations of living Syrphidae in the eastern United States 
confirm this view. I have seen very few non-mimetic syrphids which 
have or appear to have long antennae. In life the species mentioned 
above are remarkably vespid-like both in general appearance and be- 
havior. However, they are not necessarily precise mimics of a par- 
ticular species of vespid. I would, nevertheless, consider them to be 
specialized mimics which exhibit a number of different adaptations 
which imitate salient features of vespids. For example, of the four 
mimetic species illustrated, all have a more or less distinct dark area 
along the leading edge of the wing, suggesting the dark band pro- 
duced by the longitudinal folding of the vespid wing at rest. The 
four species illustrated also have either a constriction at the base 
of the abdomen or markings which suggest such a constriction. 
It is noteworthy that stylate antennae occur in only three of the 
88 genera ( Ceriana , Tenthredomyia and Callicera) and 17 of the 
939 species of North American Syrphidae listed by Wirth et al. 
(1965). The genera Ceriana and Tenthredomyia include thirteen 
species which occur in America north of Mexico. All are wasp 
mimics. There are four species of Callicera in the same area. The 
one species which I have seen is not a wasp mimic and is probably 
not mimetic at all. 
In my experience syrphids which mimic bees neither have nor give 
the appearance of having long antennae. From observations of living 
