In order to form a clear conception of these variations, reference may be made to the engraving on the next page, in which we have caused to be represented the five different kinds of pupæ, as they were named and classified by Linnæus. This plate will sufficiently manifest the necessity of an explanation upon the subject of the variations of pupæ; for few persons in examining it would form the remotest idea, that all the insects there represented are really and truly in the pupa state. Some look so like the perfect insect, that it would be almost impossible for any one only slightly acquainted with insect history to believe them to be in what is in reality a transition stage from the larva to the perfect form. [Illustration: _Various forms of Pupæ._] I. The insect, No. 1, is a pupa called the _Complete_, because it is _active_, and has many of the parts of the perfect insect. The pupa of the spider is an instance. II. The insect, No. 2, is a pupa called the _Half-complete_, or semi-complete. It is also active, resembles the perfect insect, but has only the rudiments of wings. The grasshopper is an instance of this kind of pupa. III. The insect, No. 3, is a pupa called the _Incomplete_. It is _inactive_, but possesses rudiments of legs and wings. The common wasp is represented as an example of this kind. IV. The insect, No. 4, is a pupa called the _Obtected_.[K] This pupa has its upper portion encased in the peculiar manner represented, the chest and lower portion being distinct. The butterfly pupa belongs to this division. V. The insect, No. 5, is a pupa called the _Coarctate_.[L] In this case the pupa is enclosed within its larva skin, which forms a globular or oval case, the pupa lying loosely in it as if it had shrunk to a smaller size. The pupa of the blow-fly is an example. Such are the five variations of pupæ, as they were recognised by Linnæus--the _Complete_, _Half-complete_, _Incomplete_, _Obtected_, and _Coarctate_. They are sufficiently minute for ordinary purposes: and it will possibly save the reader some confusion of ideas to endeavour to fix them in the memory; so that when looking at an insect whose pupa state may not be so very characteristic as that of the blow-fly, or butterfly, he may still be able to say with confidence, that although it is unlike these, it is nevertheless a pupa. On all subjects nothing is of so much importance as clearness of ideas. It is better to know only a few things, and to understand them clearly, than to have a confused and indistinct knowledge of a great number. It has been, therefore, simply and entirely with a view to obviate this state of things in the mind, that these definitions of the different kinds of pupæ, which may have appeared not altogether interesting, have been given.