time ascertain whether D. gracilis and insignis had bidentate 



labrums. 



I am happy in being able to introduce some interesting re- 

 marks connected with the oeconomy of these insects which are 

 new to me. Towards the end of August, during the late meet- 

 ino- at Bristol, Mr. Hewitson gave me some straws taken from 

 the thatch of a summer-house, each of them containing from 

 10 to 20 Hymenoptera ; a few days after, Mr. Waring took me 

 to the summer-house in his garden, when I saw multitudes of 

 small black Hymenoptera entering the straws of the thatch, 

 many of them carrying an Aphis. I secured some for subse- 

 quent examination, when I was greatly surprised to find what 

 I had supposed, whilst they were flying, to be merely the 

 sexes of one species, comprised, I believe, four genera, viz. 

 Hyhviis annularis (folio 373), males of Psen ater (fol. 25), 

 Pemphredon unicolor, and a Diodonttis. On splitting the 

 straws I found numbers of perfect insects, together with larvae 

 inclosed apparently in pollen, masses of an Aphis, and occa- 

 sionally a specimen o{ Hedychriini imperiale (fol. 38). I had 

 no opportunity of revisiting the spot after I found there 

 were several genera whose habits were so similar ; I therefore 

 have some doubt whether I did not take the Hylceus and Dio- 

 dontiis out of the straws. I am pretty certain it was the Pem- 

 phredons that were carrying the Aphides, which I believe were 

 taken from a rose-bush. The Hedychmm was in all proba- 

 bility a parasite of the Hylaeus. The British Pemphredons 

 may be thus divided. 



* 1st and 2nd subinarginal cells, each receiving a recurrent 



nervure. 



1. LugubrisZvzi. — Lat. — \m\co\or Jur. Gen. 28.J9/.11 ? . Black, 



sinning, clothed with white pubescence, thickly punctured, except the 

 abdomen and legs : antennre thickened a little at the middle in the 

 males, with the clypeus silvery : ^ 4, ? 5 lines long. 

 Beginning of June, old paling and trunks of dead trees. 



2. morio Va7id. Lind. part l.p. 82. n. 5. " Black, clothed with 



griseous pubescence, the abdominal petiole short : 3 lines long." 



** 1st marginal cell receiving 2 recurrent nervures, the 



2nd none. 



3. unicolor Fab.— Curt. Brit. Ent.pl. 632. S- As this is not 

 the S. unicolor of Panz., the Fabrician name of ater ought 

 not to have been superseded. Shining black with whitish pubes- 

 cence, head thickly punctured, clypeus silvery in the male, thorax spa- 

 nngly punctured before, nietathorax with a shining elevated semicir- 

 cular Inie, petiole punctured and channelled : wings tinged with brown, 

 especially the apex of the anterior. 



May and June, Oaks, Coomb-wood and Lowestoft; 28th 

 July, Casde Connel; 8th July, under the Cliff, Dover; end 

 of August, about the thatch of a summer-house, Bristol. 



For specimens of the rare plant Caucalis latifolia. Broad- 

 leaved Hcn's-foot, I am indebted to Miss Queckit, who ga- 

 thered them ni a corn-field near Langport. 



