1929 ] Use of Terms Parapsides and Parapsidal Furrows 377 
a portion of the mesonotum of P. billardieri Fabr. bearing 
the parapsides and parapsidal furrows taken from Mac- 
leay’s original figure and is enlarged to twice the size 
of his figure. In his explanation of the plate he designated 
the parapsides of the mesonotum with the Roman numeral 
II. Since it is perfectly clear from his figure as well as from 
his description (page 148, footnote 1) that he intended the 
term parapsides to be applied to the lateral regions of the 
mesonotum delimited by the longitudinal (parapsidal) fur- 
rows, it is logical that all homologous regions and furrows 
in other Hymenoptera should be similarly designated as it 
Fig. 1. Portion of the mesonotum of Xiphydria. 
Fig. 2. Portion of the mesonotum of Ampulex. 
Fig. 3. Portion of the mesonotum of Polhtes billardieri Fabr. 
Fig. 4. Portion of the mesonotum of Myopopone castanea maculata Roger. 
Fig. 5. Portion of the mesonotum of Paraponera clavata F. Sm. 
is one of the important principles of comparative morphol- 
ogy to apply the same term to the homologous anatomical 
parts in different groups. 
If all Hymenoptera had a mesonotal structure similar to 
that of P. billardieri Fabr. the matter would have been much 
simplified and no confusion would have resulted in the litera- 
ture. However, in certain Hymenoptera ( Xiphydria , Am- 
pulex, Paraponera, Figs. 1, 2, and 5) another pair of longi- 
tudinal furrows appears extending backward from the ante- 
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