4 Mr. W. J. Kaye on 
was quite conspicuous. This remarkable structure recalls 
the ovipositor of a parasitic hymenopteron, but no such 
possible model was observed. 
Fig. 4 is Pseudosphex noverca, Schs., and fig. 4a is 
the model Polybia nigra, Sauss., a Vespid wasp. This 
Vespid was not taken by me with the Pseudosphex, but 
Mr. C. Schrottky has taken the two together on Ageratum 
conyzoudes in Paraguay. This same plant, which is very 
abundant in 8. Brazil and Paraguay, always attracts a 
large number of Syntomidae, as well as wasps of both the 
families Vespidae and Eumenidae. It was on this same plant 
that the Pseudosphex was taken together with a Kumenid 
wasp, Zethus binodis. The mimicry of these two is remark- 
able even when they are sitting together as I found them, but 
the Vespid species Polybia nigra is even better, and it is 
most probable that it also occurs where I took the Eumenid 
at Fernandez, for it has a wide range. The wonderful 
special development of the Pseudosphez is first of all worth 
describing. First there are the antennae, which in the 
stout pectinated portion are just about the length of the 
wasp’s antennae. The fine thread-like tip to the antenna 
of the Syntomid is hardly visible except one is looking 
very close. In the figure the pectinations end too gradually, 
the specimens showing that the pectinations end rather 
abruptly, giving the antenna at a short distance the exact 
build of a wasp’s. This characteristic is shown better 
in fig. 5 of Pseudosphex jonesi, but even then the thread- 
like end is not fine enough. The very marked constriction 
of the basal segments, the very smooth scaling of the head, 
thorax and abdomen and the colouring of both wings, 
thorax and abdomen altogether makes these moths most 
wasp-like. In all of them, also, the profile view of the head 
is remarkable, for the palpi are densely scaled on the first 
and second joints, so that the strong jaws of the wasp are 
most completely imitated. In profile the general resem- 
blance is most complete, for in every way there is imitation 
of the wasp. When viewed above only, is the larger head 
of the wasp distinctive. 
The habits of the species of Pseudosphex are equally 
remarkable with their structure. Of the four species 
figured no less than three, P. novercida, P. noverca and P. 
polybiordes (figs. 3, 4 and 6), occurred together at Fernandez, 
while the fourth, P. jonesi (fig. 5), was found at Alto da 
Serra. All the species were found to visit the flowers of 
