EXTERNAL ANATOMY OF INSECTS. 403 



present the greatest differences; and, owing to the accurate 

 and elegant manner in which my friend Mr. Ingall has en- 

 graved them, the reader will not fail to observe how beautifully 

 simple and unvarying is the foundation on which nature builds 

 structures so wonderfully and elegantly diversified ; it seems 

 as though a certain portion of matter were allotted, out of which 

 she has to mould every variety of form.'' 



In naming the segments I have found two difficulties to 

 contend with ; first, the fear of introducing a new name where 

 an old one had been pretty well established ; secondly, the 

 adoption of any name the meaning of which conveyed a false 

 impression ; these, however, I have not been altogether able to 

 avoid without causing unnecessary inconvenience and confu- 

 sion; your readers will therefore be kind enough to recollect 

 that the six segments following the head are not named with 

 any view to convey a sound and universally applicable meaning in 

 their names, but to avoid any clashing with previous nomen- 

 clature : the remaining six, on the contrary, convey a meaning 

 which I have endeavoured to render as simple as possible : 

 the similarity in the meaning of the name given to the eleventh 

 and twelfth segments will perhaps be pardoned when it is 

 shewn that each in turn becomes the penultimate segment. 

 In perusing these remarks, however, I could wish your readers 

 to abstain from attempting to apply meanings, and to consider 

 the whole as unmeaning words, the numerical situation being 

 the only circumstance tending to illustrate the subject.' 



The first segment of all insects is the Caput, or head, the 

 hinder part of which generally forms a considerable portion 

 of a sphere ; the fore part is variously formed. On each 

 side, immoveably fixed in it, and sometimes occupying the 



' See Plate III. As the whole of the segments, in the perfect state, must be 

 figured in the illustration of their parts, I thought it would be unnecessary to give 

 figures of them here. " One of the most beautiful facts that the study of com- 

 parative anatomy presents us with, is the delight nature appears to take in work- 

 ing as it were with a given quantity of material, while she, nevertheless, produces 

 an infinite variety of forms." — MacLeay, Zool. Journ. XVJII., p. 157. 



' If in any instance I have introduced a new name where a previous name could 

 possibly, I will not say properly, be retained, it has been entirely through negli- 

 gence, and I shall be most willing to withdraw it when pointed out ; for (in com- 

 mon I hope with all naturalists) I consider that the alteration of names once 

 given is, of all scientific labours, the one most conducive to confusion and error, 

 and one which no lover of science would intentionally commit. 



