564 DP. R. C. L. PERKINS ON THE 
the species form a number of distinctive colour-groups, which are 
quite different from the groups formed by them when characters 
of structure are considered, Particularly interesting are the 
species of the second division of the genus as arranged by me, 
since several of these closely resemble small species of Australian 
Icaria, social wasps, which are found in the same localities. 
‘he resemblance is rendered far more perfect from the fact that 
in these Paralastor the basal abdominal segment is reduced in 
size and is less wide than usual, so that the abdomen approaches 
in form that of some of these social wasps. 
As to the other division of Paralastor, the species not only form 
colour-groups amongst themselves, but these groups mostly, and 
perhaps all of them, reproduce the colours and patterns of other 
genera of solitary wasps, Odynerus, Rhynchiuvm, and Abispa. 
Even the bees of the genus Hylaeoides (Prosopide) are drawn 
into these colour-groups, and both in these bees and some of the 
Odynerus the resemblance extends beyond the matter of colour, 
so that certain peculiarities of structure are reproduced in all. I 
have elsewhere (Ann. & Mag. N.H. (8) ix. 1912, p. 108, Hylacoides, 
and p. 121, Abispa) referred to cases of this structural mimicry 
combined with mimicry in colour. How great is the resemblance 
may be judged from Saussure’s description of Alastor fraternus, 
of which he says: ‘‘ Presque identique par la coloration avec les 
Odynerus clypeatus et concolor; formes les mémes,” ete.; but this 
case, naturally, does not compare in interest with that of the bee 
HHylaeoides, where structures identical with those of Paralastor 
are assumed, these structures being unique in that family of bees 
to which Hylaeoides belongs. In the case of the Odynerus and 
other Eumenid genera, where structural and colour mimicry are 
combined, we are at least dealing with members of a single 
family, however distinct the genera themselves may be. 
All the species of Paralastor from Tasmania that I have myself 
seen, are extremely similar in appearance, with nearly white 
markings and two very narrow abdominal bands. Odynerus of 
quite similar appearance were taken with these by Mr. R. E. 
Turner last year. 
In N. Queensland, P. optabilis, which has a coloration entirely 
unlike any other Queensland species of its genus, is mark for 
mark the same as an Odynerus occurring with it, and both have 
similar structural peculiarities. 
At Adelaide in 8. Australia and in Victoria are numerous 
species with deep dull orange or red markings, superficially either 
entirely or nearly resembling one another, though falling into 
the most diverse structural groups. These species seem to vary 
in their patterns individually, and it would appear that different 
species exhibit similar variations of pattern. 
Orange-marked species (though found elsewhere) are abundant 
in Queensland, while W. Australia has a very distinct colour- 
group, the thorax of the species being largely red, and the basal 
abdominal segment similarly coloured, while the rest is black. It 
