ART. 9 DIGGER WASPS OF GENUS PODALONIA FEKNALD 3 



the median line posteriorly, with the area near the tip of the shield 

 liable to show an inclination to transverse ridges again. The punc- 

 tures may be coarse, medium, or fine. When coarse and close 

 together, which is particularly liable to be the case anteriorly and 

 near the median line, all traces of the ridges may be lost and a con- 

 fused appearance of the surface results. Where a tendency for the 

 punctures to lie in transverse rows develops, irregular transverse 

 ridges may develop between the rows of punctures. The punctures 

 are liable to become smaller at the side behind the spiracle and near 

 the tip, and here the ridges are generally finer. The posterior end of 

 the propodeum drops off sharply from the tip of the shield to the 

 articulation of the petiole. Between these points is often a small in- 

 dentation or fovea, varying in size. The surface of the end is punc- 

 tured and may be more or less ridged, the ridges, when present, being 

 most evident running downward at the sides of the petiole. The 

 sides of the propodeum are directly continuous with the end and 

 resemble it in markings, though there is a greater tendency to the 

 production of ridges on the sides than at the end or on the shield, 

 particularly near the propodeo-mesopleural suture, the ridges running 

 downward and often somewhat forward. 



Where the sides of the propodeum are plainly ridged, this condi- 

 tion is likely to continue on to the metapleuron, the ridges running 

 less downward but more nearly along the body. A small, more or 

 less separated portion of this plate, lying at its upper anterior end 

 beneath the hind wing, is often nearly or quite free from punctures 

 and more noticeably ridged than the other portions. The ridges 

 may extend entirely across the plate and continue more or less on 

 the mesopleuron, or may end at the meso-metapleural suture. The 

 mesopleuron is generally quite closely and coarsely punctured, but 

 ridges on it are usually restricted to that portion adjacent to the 

 metapleuron. A somewhat triangular portion beneath the fore wing 

 may show few punctures and be rather distinctly ridged. 



The main mass of the abdomen is connected with the propodeum 

 (and thorax) by a slender, cylindrical stalk, the petiole. In this 

 genus the petiole consists of only one segment (two in Sphex) and is 

 apparently only the sternum. At its front end a muscle, attached 

 just above its articulation to the propodeum, attaches to the upper 

 side of the petiole a short distance out and acts as a levator muscle. 

 At its posterior end the petiole broadens out below, forming a sort of 

 flat, spatulate area. Over this portion is apparently the notum of 

 the segment. This rises quite rapidly from the axial line of the pet- 

 iole ("somewhat bell-shaped," Kohl) and is quite wide, its lateral 

 margin hanging down over the ventral plate. In this notum is a 

 spiracle located in front of, or at most, at the middle of the length 

 of the plate. 



