VI PREFACE. 



In all instances I have done my best to verify the records whenever 

 such a course has been practicable ; but the great number of species still 

 relying solely upon Stephens' British records must be regarded with 

 suspicion, since the nomenclature has, more recently, undergone such 

 radical emendations and his species have so often been sub-divided. 



'i'he great stumbling block in the study of Ichneumons is the difficulty 

 with which their identification is fraught. In the Coleoptera, &c., 

 the distinctions are often extremely minute, though nearly invariably 

 easily perceptible when seen in a favourable light ; in the present 

 insects, however, the distinguishing features are often, like those of 

 many members of the genera Homalota and Longitarsus, extremely 

 hard to define, though the several kinds are different enough to the 

 trained eye. One of the dangers of determining Ichntunions from 

 mere descriptions, more even than other insects, on account of their 

 great similarity to one another, is that of forcing specimens into 

 descriptions with which they agree in most points though not entirely ; 

 and this is augmented by the wide range of variation both in structure 

 and colour which some species exhibit. Imagination, tempered with 

 caution, is a most useful factor in determination and will transmit 

 from the description a figure of the insect and its parts to one's mind, 

 with which the specimen before one must agree in every detail, or at 

 least in all essential characteristics. Negative descriptions, in which 

 are mentioned only those points not shared by allied species, such as 

 Professor Thomson's, are of the utmost service, but hardly suffice the 

 average student, who therein often feels the want of a general idea of 

 the insect's facies. I have endeavoured to give a positive description, 

 sketching the insect under consideration in such a way as to convey 

 its word-picture, and have in most instances afterwards drawn attention 

 to the points peculiar to it. In treating of a subject so little known, 

 at least in Britain, as the present, it is better to present as full an 

 account as possible of each species, provided discriminating features 

 be also indicated, the omission of which so greatly stultified the utility 

 of the older authors ; moreover, it is most puzzling to find but a few 

 features mentioned, and appended a note to the effect that the remainder 

 are analogous with those of the preceding, which, in turn, carries one 

 yet further back, and so ad nauseam. 



The disparity of the sexes is more marked in the insects iiere dealt 

 with than, perhaps, in any other branch of Entomology. To so great 

 an extent is this usually the case that nearly all the modern authors 

 continue to describe the sexes individually, and the old writers con- 



