300 A. L. MELANDER. 



with straggling, whitish, longer hairs. Disc of the first segment of the abdomen 

 impunctate dorsally, margined however by setigerous punctures; ventrally the 

 first segment has close, deep punctures, anterior half of the keel obliquely promi- 

 nent, deeply excised at its middle; seen from above, the petiole is trapezoidal, 

 the anterior angles but little produced, subacute, posteriorly subsessile with the 

 second segment; from the side this incisure is not pronounced; second abdomi- 

 nal segment with subcontinent punctures, its anterior and posterior margins and 

 a median vague line piceous, anteriorly with appressed black pubescence and 

 long, stiff, black hairs, the posterior margin likewise clothed, but the erect hairs 

 are brown and short, elsewhere covered with appressed pubescence and short, 

 stubby hairs concolorous with the vestiture of the thorax but less dense; ground 

 color of remaining segments blackish, the pubescence of the third dorsal black, 

 of the others whitish ; the suberect hairs of the venter, tibia? and tarsi whitish ; 

 pygidium formed as in texana, with reflexed margin, truncate tip, and longitudi- 

 nally striate disc, the stria;, however, deep and entire, reaching the entire length 

 of the pygidium. 

 Length, 9 mm. 



Plate IV, fig. 21 ; petiole. 



Several specimens, central Illinois, collected near the town of 

 Bath, on the Illinois River, August, 1899. 



While this species would lead to the group (species 42-50) 

 defined by Mr. Fox as having the second segment of the abdomen 

 subsessile with the petiole, and the head comparatively small, vet 

 its general habitus is much more suggestive of texana Blake. 

 However, it is quite distinct from that species in the structure of 

 the keel of the first ventral segment, the longer strise of the pygidium, 

 the shorter third joint to the antennae, and the denser pubescence of 

 different color. In texana, the carina ends posteriorly in a distinct 

 tubercle, while the anterior blade is entire ; the striae of the pygidium 

 are weak and abbreviated ; and the first flagellar joint is one half 

 again longer than the second, while the metathorax is less abruptly 

 declivous. 



34. Mutilla obscura Blake (53 and 70;. 

 Mutilla obscura Blake. % . 

 Mutilla scsecola Blake. 9 . 



Plate IV, fig. 26 ; petiole of male. 

 The Rev. Mr. Birkman has fortunately been able to associate 

 these two species as sexes of the one form. Both males and females 

 are not rare at Fedor and Austin, Texas. April to June. 



Another male was obtained by Dr. Wm. M. Wheeler at Bull 

 Lake, Wyoming. The Museum of Comparative Zoology has both 

 the female and the male from Massachusetts. 



