THE 



^y^ VOLUME XVI. Vl/^ 



NOTES ON THE GENUS CCELIOXYS, K^Y) AN ADDITIONAL SPECIES 

 TO THE LIST OP BEITISH EYMENOPTERA. 



BY EDWARD SAUI^DERS, P.L.S. 



This genus is well known to Hymenopterists by the curious eix- 

 spined apex of the abdomen of the (^ (JST.B. : the spines are on the 

 6th segment) and the acuminate apex of the $ ; but the species 

 bear such a strong general resemblance to each other that they are 

 probably more or less mixed up in many collections. 



On the continent there are two distinct sections of the genus, one 

 of which only we have found in England at present, the first in which 

 the white bands of the body are formed of scale-like hairs, and the 

 second containing our British species, where the hairs are of the more 

 usual type, although very beautifully feathered. The hairs of the 

 species of this genus are well worth the trouble of examination. The 

 scale-like hairs of section 1 consist really of a mid-rib with hairs 

 branching from it in several directions, but these branches are packed 

 so closely together, that a dense oval mass is formed which, under a 

 low power, looks far more like a scale than the ordinary hair of a bee. 



We, at present, know of 5 British species : — No. 1, vectis, is one 

 of the largest, only being equalled in size by large rufescens ; it may be 

 known from all the others by the blunt end of the external spine of 

 the posterior tibiae : this may seem a slight character but it is most 

 constant and easily observed. The other 4 species can be divided into 

 2 sections. The 1st, containing 4<-dentata and rvfescens, has the apex 

 of the 4th segment of the body beneath in the $ deeply emarginate, 

 and the 5th segment in the ? rounded at the apex; the 2nd, containing 

 simplex and acuminata, Nyl., has the 4th segment entire in the 

 (^, and the 5th segment in the ? truncate at the apex, ^-dentata 

 differs from rufescens in having no lateral tooth at the apex of the 5th 

 segment in the $ , and the apical ventral valve in the $ elongate and 

 lanceolate, whereas, in rufescens, it is shorter and triangularly truncate 

 at the apex. I look upon umhrina, Smith, as only a small form of 

 rufescens. 



E, 1879. 



