J. H. MERRILL 131 



Megarhyssa mexicana (Cresson) 

 Epirhyssa mexicaiia Cresson, Proc. Acad. Nat. Sci. Phila., 1893, p. 394, 9 . 



No statement about the types accompanies the description, 

 but a range in length measurement impHes that more than one 

 specimen was examined and there are two specimens labeled, 

 "Type No. 599," from Mexico, in the collection of the American 

 Entomological Society of Philadelphia. 



9 , This species is about an inch long, with an ovipositor a httle longer 

 than the body. The head is yellow but the mandibles are black. The region 

 in which the ocelh are imbedded and extending between the compound eyes 

 is slightly darker than the ground color of the head. Parallel and posterior 

 to this darkened area is a dark band which nearly encircles the head. The 

 sutm-e from the compound eyes to the mandibles and extending across the 

 upper part of the clypeus is also dark. The antemiae are dark brown, except 

 the under side of the scape which is Ughter colored than the flageUum. 



The gromid color of the thorax is pale yellow. The sutures separating the 

 mesonotum from the prescutum, prothorax and mesoscutellum are dark. 

 A dark band runs along the center of the prescutum and another on each side 

 of the mesonotum runs from the prescutum back to the mesoscutellum. The 

 suture separating the mesothorax from the metathorax and the propodeum 

 is also dark. The legs are yellow and the tarsi become darker toward the 

 tarsal claws which are dark brown or black. The suture dividing the posterior 

 femur from its trochanter is dark. The wings are faintly yellow-hyaline, 

 clouded at theii- tips and without an areolet in the specimens examined. 



The abdomen is yellow, smooth, and ghstening. The tips of the second, 

 third, fourth, fifth and sLxth segments are each bordered with a black band. 

 In the remaining segments these bands are nearly obsolete. The ovipositor 

 is dark brown. 



Male unknown. 



Distinguishing characters. — Mexicana may be distinguished 

 from the other species of Megarhyssa by its yellow abdomen 

 without spots and probably by the absence of the areolet in its 

 fore wings. 



This species was placed in Epirhyssa by Cresson, but the struc- 

 ture of its sternal plates agrees with those of Megarhyssa and the 

 presence of the areolet seems to be a variable character in thip 

 group. 



Megarhyssa nortonii (Cresson) 



Rhyssa nortonii Cresson, Proc. Ent. Soc. Phila., iii, p. 317, 9 . 



Thalessa quebecensis Provancher, Natural Canad., v, 1873, p. 317, 9 cT. 



Thalessa nortonii Provancher, Faun. Ent. Canad.; H\'men., 1SS3, p. 445. 



TRANS. AM. ENT. SOC, XLI. 



