22 
Psyche 
[March 
yellowish abdominal markings are lost. This coloration, in 
combination with the shape of the body produces the really 
astonishing resemblance between the fly and wasp, since 
most of our common “Ammophilas” have the conspicuous 
red basal abdominal marking. 
The African species are in general colored like the 
Nearctic ones with the ferruginous color sometimes extend- 
ing conspicuously on to the thorax, although pale spotted 
ones are known also from this continent. 
Among the species known from the Neotropical region 
the thorax may be conspicuously marked with whitish or 
yellowish or this pale pattern may be almost entirely sup- 
pressed. They are thus intermediate between the “vespoid” 
and “ammophiloid” series. 
A Tasmanian species, S. clavifemoratus Hardy is of the 
unspotted type and also one from Madagascar while S. studyi 
Enderlein from South China is said by its describer to re- 
semble Ammoyhila atriyes. 
If then we consider the species from the several zoological 
regions together the development of two such divergent 
mimetic types is not so surprising for each appears to rep- 
resent a modification of not such very great extent from a 
somewhat intermediate pattern. As the “ammophiloid” 
type is more widely distributed, extending even into the 
Australian region, we may consider the development of 
conspicuous yellowish spotting as the more recent pattern. 
