542 Insects. 



always borne in mind, that it is sometimes exceedingly difficult to 

 draw the line of demarcation ; and that subsequent discoveries gene- 

 rally give birth to such charges, which must and will continue to be 

 the case. I have been led to make these observations, from a fear 

 that I may be considered as running into the opposite extreme ; and 

 that for the sake of novelty, and a love of change, I have destroyed 

 what others have carefully formed ; but I will not differ from any au- 

 thor without such proofs as convince me of being right, or from such 

 reasonable deductions as leave no doubt on my own mind of the cor- 

 rectness of my views. 



The species of the genus Bombus are indeed difficult to be deter- 

 mined, and the difficulty is increased from the colour of the hairs be- 

 ing so liable to change ; in addition to which, the same sex is some- 

 times clothed in a variety of colours, varying from a bright and gaily 

 coloured insect to one totally black ; and it requires a considerable 

 intimacy with (if I may use the expression), and an extensive col- 

 lection of specimens, to enable any one to link the chain of varieties ; 

 nor can I by any means flatter myself that I have not fallen into 

 some errors arising from these causes. One very fruitful source of i 

 error has been the practice of describing specimens which had been 

 long disclosed, the hairs entirely changed from their original colour, 

 the wings lacerated at their margins, and no mention made of the sex 

 of the insect described. Mr. Kirby has noticed several such in- 

 stances, and properly rejected such species. 



My connexion with the Entomological Society affords me constant 

 opportunity of examining the original specimens from which Mr. 

 Kirby drew up his descriptions for his Monograph, the whole of them 

 being deposited in the Museum of that Society. I have also careful- 

 ly examined both the Linnean and Banksian collections. These aids, 

 and a close attention to the aculeate Hymenoptera, will I trust enable 

 me to place the genera in somewhat better order than they have hi- 

 therto been in. 



It is not my intention to describe all the species ; indeed that is 

 rendered unnecessary by the admirable descriptions in the 'Monogra- 

 phia Apum Angliae.' Descriptions are given of all the new species. 



Genus. — Apathus, Newman. 

 Psithyrus, St. Fargeau. Bombus, p. Latreille. 



The males of the genus Psithyrus may be distinguished from those 

 of Bombus by the convex posterior tibiae thickly granulated and 

 coated with hairs : in the genus Bombus the posterior tibiae are con- 



