CHARLES W. METZ. 153 



EXPLANATION OF PLATES. 



All figures are drawn to scale with the camera lucida. The 

 face drawings are all enlarged the same amount, to show- 

 relative sizes, and proportions. Likewise the genitalia 

 figures have all received equal magnification. 



In comparing the facial figures account must be taken of 

 the angle at which the head is placed, and the direction of 

 the antennae. In some the face is tipped slightly forward or 

 backward, as shown by the eyes and antennal sockets ; this 

 tends to shorten the clypeus somewhat. Similarly the scape 

 may be slanted upward, or even somewhat downward, and 

 consequently changed a little in proportions ; this can be dis- 

 tinguished by the apical margin, which is concave if high 

 and convex if low. An apparent discrepancy is also notice- 

 able in some cases where the broad surface of the scape is 

 in view in one drawing and the narrow surface in another. 

 In general, however, when the position is not normal the fact 

 is evident from the figure, or attention is called to it in the 

 text. 



In the figures of genitalia the sagittse often appear dis- 

 torted, owing to their extreme delicacy as mentioned before, 

 and apparent differences will be seen where none exist, so 

 these cannot be relied upon. Similarly the stipites in some 

 figures diverge noticeably, but this is merely due to the in- 

 dividual mount and not characteristic. Darkened areas in 

 the eighth ventral plate vary considerably with the amount 

 of clearing which the specimens have undergone, and are of 

 no importance, except in such cases as are noted in the text. 



Plate II. 



11. P. zizice. Genital armature. 



12. P. modestus. Genital armature. 



13. P. episcopalis . Genital armature. 



14. P. fossata. Genital armature. 



15. P. conspicua. Genital armature. 



16. P. rudbeckice . Genital armature 



17. P. varifrons. Genital armature. 



18. P. tridentiilus . Genital armature. 



19. P. grossicornis . Genital armature. 



20. P. calvus. Genital armature. 



TRANS. AM. ENT. SOC. , XXXVII. (20) 



