i64 HYMENOPTERA ACULEATA. 



(SuBQ. ANCISTROCERUS.) 



0. calloSUS, Thorns, {quadratus Smith, nee Panz ?). — 

 Black, punctured, clothed with greyish hairs ; mandibles 

 and clypeus in the ^J yellow, margined with black, the 

 former deeply emarginate, in the ? black often with two 

 or four yellow spots on the latter, its apex almost truncate, 

 Bcape of the antennte in front, a spot between the 

 antennae, and generally a small spot behind each eye, in 

 both sexes, yellow ; pronotum with an apical band, the 

 scutellum generally with two spots, a small spot on each 

 tegula, and often a spot on the mesopleurse yellow ; ab- 

 domen slightly shining, clearly and distinctly punctured, 

 all the segments except the terminal one with a yellow 

 apical band, that on the first suddenly and rectan- 

 gularly dilated at the sides, second ventral segment 

 with the longitudinal costse of the transverse sulcature 

 rather long, its surface beyond the sulcature suddenly 

 elevated and angulated, and then straight or slightly 

 concave to its posterior margin ; femora yellow at the 

 extreme apex, tibite and tarsi yellow, the former sometimes 

 black at the apex inwardly. All the markings are liable to 

 variation. 



L. 9-13 mm. 



One of our commonest species, but often confounded 

 with the following — the form of the basal abdominal band 

 in this species is pretty constant ; but the same form 

 occurs m parietum, trifasciatus, and pdCi'ehHws, so that it is 

 not to be trusted as a specific character. 



0. parietum, Linn. — Very like the preceding, but rather 

 more robust, the basal segment of the abdomen being pro- 

 portionately rather wider ; it is very variable in colour, so 

 that no dependence can be placed on that character, the 

 band of the basal segment of the abdomen is, however, as 

 a rule, angularly not squarely notched in the centre; the 

 form of the second ventral segment of the abdomen will 



