INTRODUCTION. XIU 



quilius (Syst. Nat. ii. 558.— Faun. Suec No. 397.), and the female 

 Coccinella ! unipunctata (Syst. Nat. ii. 579. — Faun. Suec. No. 470.) ; 

 which is the more to be wondered at, as, from the insect being far 

 from uncommon in Sweden, he might have had frequent oppor- 

 tunities of detecting the identity of the sexes. But in the instance 

 noticed from Mr. MacLeay, the insect in question is a native 

 of South America, and consequently the writer had no means of 

 ascertaining any portion of its history, but was subsequently in- 

 debted to the observations of Mr. Swainson, whose zeal for ento- 

 mology led him to explore the distant region of Brazil, for correct- 

 ing the mistake into which he had accidentally fallen *. But as 

 I have elsewhere advocated the expediency of generic division, I 

 shall proceed to give some cursory observations upon species, and 

 upon the difficulty of discriminating them. It cannot be denied that 

 much obscurity prevails upon these subjects : it therefore becomes 

 the duty of every inquirer to endeavour to dispel the mist, and to 

 contribute his mite towards their elucidation; though I do not 

 assume that such should be the sole object of every one. I would 

 rather that attention should be paid to the economy, &c. of the 

 interesting objects of the entomologist's research; though I would 

 ask, how can an individual communicate to others the knowledge 

 he has acquired by his observations, unless he be able to define with 

 accuracy the very animal which furnished it ? Upon this con- 

 sideration, therefore, it is manifest tbat an examination into the 

 true distinctive characters of species should occupy at least a portion 

 of his time, instead of devoting it almost exclusively to searching 

 after the relationship of affinities, — which has been so much insisted 

 on by late writers, almost to the total exclusion of specific investi- 

 gation ; or in generalizing upon structure before he is acquainted 

 with particulars. 



In pursuing this investigation, the firstquestion which presents 

 itself is. In what do the characteristics of a species consist ? I need 

 scarcely add, that its solution is one of the utmost difficulty, as the 

 characters of many species are very obscure, and are not readily 

 detected, owing to the innumerable variations to which they are 

 subject from age, locality, or climate, or from the close approxima- 

 tion of those in kindred species. Of the latter description, the 

 genus CucuUia (part ii. p. 102.) offers a remarkable example; most 

 of the species of which it is composed resembling each other so 

 closely in their final state, that were it not from a knowledge of them 

 during their previous appearance (their larviE being totally dissimi- 

 lar, and their food and time of flight very different), they might 



* A more recent example, however, occurs in a work which assumes 

 superior accuracy in the generic distribution of insects; in which the Musca 

 putris of Linne is converted into three species belonging to two genera. 

 Vide part ii. p. 319. Nos. 9126 and 9140. 



