74 
Psyche 
[June 
swelling of the terminal segments of the flagellum into a 
club. But this is far from being the rule, since the antennae 
of Trimeria, Microtrimeria, Ceramius, Paraceramius, Cera- 
mioides, Paragia, and Metaparagia have the flagellum not 
more swollen than many members of the other subfamilies. 
The equal number of antennal segments in both sexes 
should, I believe, be regarded as primitive. 
The mouth-parts are of two distinct types. In Paragia 
and Metaparagia , they have retained the more primitive 
condition, as is also the rule among the other subfamilies of 
Vespidae: the ligula is short and not retractile, composed 
of two short glossae which are but little longer than the 
paraglossae; the palpi are well developed, the maxillary 
palpi 6-segmented, the labial palpi 4-segmented. In the re- 
maining genera of Masaridinae, the mouth-parts are highly 
specialized, being modified into a proboscis, or sucking- 
tube, composed of the elongate, retractile glossae which are 
much longer than the paraglossae; when withdrawn in the 
buccal cavity, the labium forms a loop which may enor- 
mously distend the membrane of the neck ; the maxilla, how- 
ever, remains short, and there is often a reduction of the 
number of segments of the palpi. This modification of the 
trophi is, as we shall see, correlated with the highly 
specialized, anthophilous diet of these wasps. Unfortunately 
the habits of Paragia and Metaparagia are as yet entirely 
unknown, but it is possible that they may show some 
relation to the different structure of their mouth-parts. It 
should be noted that the proboscis of the anthophilous 
Masaridinae, although having the same function as that 
of the Apoidea, or bees, has a different morphology, since 
the maxillae and labial palpi never form any part of it. 
The most striking feature of the thorax is the unusual 
development of the scutellum which shows a tendency to 
overlap and crowd out the postscutellum. This character is, 
however, present in Euparagia also. The parapsidal furrows 
are completely preserved in some genera ( Trimeria , Mi- 
crotrimeria , Paragia, Masariella, Ceramius) ; in others they 
are indistinct ( Paraceramius , Jugurtia) or absent (Ma- 
saris, Pseudomasaris, Celonites) . The mesepisternum may 
either show the primitive division into an upper and a 
