304 E. T. CRESSON, JR. 



joints of post-tarsi in proportion 1:2; femoral spines distinct apically. 

 Wings short hyaline, with colored stigma (Fig. 137). Length, 3.5 

 mm. ; wings, 4.0 mm. 



Type.— Norwich, Vt., July 8, '08 {Johnson, B. S. N. H.). 



Similar to acuminatus, but less shining ; front more sil- 

 very ; longer fifth abdominal segment, and fifth costal section 

 equalling third and fourth together. It is at once distin- 

 guished from appendiadatus by the normal occiput. 



26. P. liiticliventris Loew. 



Described from the District of Columbia ; also reported 

 from New Hampshire (1895 Slosson 320) and Canada (1901 

 Chagnon 13). 



I do not know this species, which seems to consist of all 

 females. None of the specimens examined in the material 

 at hand seem to fall under this form, except those I have 

 placed in the following species, horvathi Kert. Both these 

 forms may be distinguished from among the females by the 

 black (?) humeri, the shining abdomen and the black femora. 

 Neither Loew or Hough gives the color of the humeri, which 

 I suspect are black. 



27. P. horvathi Kertesz. 



Described from New York. I have before me the follow- 

 ing specimens which seem to be this species, but are possibly 

 distinct, and are all females : Norwich, Vt.. 2 ; Boston, Mass., 

 1 (both by Johnson, B. S. H. H.); Swarthmore, Pa., 2, Figs. 

 21, 78, 162 (Cresson, A. N. S.), Taken May to September. 

 They differ from nitidiventris Loew, in the absence of the 

 pollinose stripe on the third segment, and in having distinct 

 femoral spines. The following description is based upon 

 the above specimens : 



9 . Face and lower part of front silvery, upper part of latter shin- 

 ing with fine median groove ; occiput cinereous. Antennae black, 

 acute (Fig. 21). Mesonotum opake or subopake, cinereous or brown- 

 ish ; scutellum more shining ; pleurae and metanotum cinereous tinged ; 

 humeri black ; halteres yellow. Abdomen polished or shining, with 

 only first and lateral margins of following segments cinereous ; each 

 increasing in length. Ovipositor yellow, gradually tapering from, and 

 hardly longer than its shining black elongate base ; extending to apex 

 of second (Fig. 78). Legs black with knees, bases and apices of 



