^0.3.] PATTON OX ACULEATE HYMENOPTERA. 3o9 



pale yellow; the amount of ferrngiiions ou the sutures of the abdomen 

 varies, the transverse depressions on segments two to live in some si>eci- 

 meus are not marked with ferruginous; the apical segment is mostly 

 ferruginous, as are also several segments of the venter. The length 

 varies from ll"^"' to 17""». 



Since 1820, when Thomas Say, while on Major Long's Expedition to the 

 Eocky Mountains, captured one male and one female specimen which he 

 described as distinct species under different genera, this species lias 

 remained uni-ecovered. In establishing a new genus for the reception of 

 those species in which the venation of the male resembles Fhilanthus and 

 the venation of the female resembles Cerceris, Mr. Cresson in 1805, re- 

 lying on Say's description, referred P. canalicuJatns to Uticcrccris, Avhile 

 he left C. hidentata in Cerceris, not suspecting that they were the sexes 

 of one species. The fine series collected by Mr. Williston enables me to 

 unite them. The ? may be at once distinguished from all other wasps 

 by the conical protuberance on the lateral lobes of the cl^i^eus. 



24. EUCEKCEEIS UNICORNIS n. Sp., 2 . 



Side lobes of the clypeus not separated from the median lobe by a 

 suture, but bounded above by an evenly arched suture, extending from 

 the fovese to the eyes, the sides of the clypeus touching the eyes. 

 Anterior margin of the clypeus armed with two remote teeth, between 

 which is a broad process equalling the teeth in length and having its 

 border sinuate and. its sides thickened ; above the process is a thin fringe 

 of bristles arising from a ridge at the base of a stout conical tubercle. 

 This tubercle arises from the basal portion of the median lobe of the 

 clyx)eus, and is of the same form and size as the tubercles arising from 

 the side lobes of the clypeus in the $ of U. canaliculatus. The man- 

 dibles have a stout but short tooth on the middle of the inner margin. 

 The labrum is narrowed anteriorly, and has its anterior border broadly 

 emarginate. The sixth ventral segment has two slightly divergent lobes 

 at the tip, the sting protruding between the lobes. The area on the sixth 

 dorsal segment narrower than in U. canaliculatus and U. laticeps. — Black; 

 the head ferruginous, tips of the mandibles, apical half of the antenme 

 and two stripes passing through the bases of the antenn;e and uniting 

 in a spot enclosing the ocelli black ; posterior margin of collar and the 

 postscutellum yellow ; tubercles, tegulai, legs, and elongate spots on the 

 sides of the metathorax ferruginous. Head and disk of thorax deeply 

 and sparsely punctured ; the side of thorax and the metathorax densely 

 punctured, the punctures running into stria) ; the area above intermediate 

 coxne finely striate, leaving no smooth triangle ; pectus sparsely punc- 

 tured ; mesopleura unarmed; enclosure at the base of the metathorax 

 polished, divided by a median groove, ii-regularly rugose transversely ; 

 abdomen deeply and sparsely punctured above, the transverse impres- 

 sions on the second, third, and fourth segments closely and finely punc- 

 tured ; a longitudinal median groove on the raised portion of the ventral 



