412 Transactions. — Zoology. 



increase the list of species even in this country ; and it stands 

 to reason that in other lands there must be many Aleurodidcz 

 ciwaiting discovery. I do not hold the opinion that the 

 interest attached to any order of insects is to be measured by 

 the number of genera and species which it at present con- 

 tains, any more than by the size and colours of the insects 

 comprised in it. Possibly the publication of these notes may 

 induce entomologists to devote more attention to these minute 

 ^nd interesting, and by no means unimportant, organisms. 



At the outset I must say that I am conscious of what 

 may perhaps be considered a serious defect in this paper. I 

 mean that in the majority (indeed, nearly all) of the new 

 species which are herein described and figured I have been 

 imable to report anything concerning the adult stage of the 

 insects. It may be thought that an account of the larvae and 

 pup£e, without a description of the imagines, is too imperfect 

 for scientific completeness and accuracy, and is thei'efore of 

 little use to science. Probably such a view might be correct 

 as regards the greater number of insect orders, and I would 

 myself admit its justice even as regards the CoccidcB, for in 

 most cases a knowledge of the immature stages of insects is 

 not much of a guide to their adult form. But in the Aleuro- 

 didcB the case is different ; and I venture to put forward the 

 following reasons for the proceeding which I have adopted : — 



1. The Aleurodidce differ but very slightly in their adult 

 stage. The form of the body, of the feet and antennae, of the 

 rostrum, of the genitalia, is but little varied in this stage, and 

 the differences which may exist require exceedingly minute 

 observation for their detection. The presence or absence of 

 spots on the elytra, and a very minute difference in the vena- 

 tion, are really about the only characters for differentiation. 



2. But, on the other hand, the fonn of the larva and the 

 pupa, then' colours and markings, and their secretions, vary 

 most considerably. A glance at the figures accompanying 

 this paper will very readily exhibit this fact. 



3. It is precisely in the larval and pupal states that these 

 insects inflict injury upon plants. Although (differing in this 

 from the Goccida) both sexes possess rostra and digestive 

 organs in the adulc state, yet it does not appear that in that 

 condition they damage plants ; that is done by the larvse and 

 pupae. It appears, therefore, more important, in the domain 

 at least of economic entomology, to bring out the differences 

 in these immature stages, so that cultivators may recognise 

 the insects in those stages in which they more particularly 

 affect plants. 



4. The point just mentioned has been probably the reason 

 why most of the species which I have received have been sent 

 to me as larvae or pupae. Aleurodidce. in these states are often 



