420 Transactions. — Zoology. 



me that he is mformed that " something analogous [to the 

 hngula] is found in certain Coleoptera adjacent to the genera- 

 tive organs, and that they are regarded as of the nature 

 of palpi." But I think that the explanation which has just 

 been given will be nearer the truth. 



As regards the waxy secretions of the Aleurodidce, I may 

 say that, in my experience, they never take the form of solid 

 homogeneous plates, as in some Coccida. Often, when an 

 Ale^irodes pupa is lifted from a leaf, a ring of wax is left 

 behind, and to the naked eye appears rather solid ; but on 

 close examination it is seen to be composed of adjacent tubes. 

 The marginal fringes and dorsal wax of larvse and pupae are 

 also not solid. On the other hand, I think they scarcely reach 

 the same degree of fineness and " fluffiness " as the secretion, 

 say, of some DactylojJtdce or Acanthococcidce, which seems 

 really like soft cotton. In chemical composition, doubtless, 

 the secretion of an Aleurodid will not differ from that of a 

 Coccid. Amongst the species described in this paper, A. 

 croceata has the most solid-looking marginal wax ; but even 

 in that close observation will detect a tubular structure. This 

 fact arises from the character of the margin in the larva and 

 pupa. The figures which I give show that the margin is never 

 quite entire, but presents a " crenulated " appearance, more 

 or less conspicuous. The " crenulations " are merely the 

 extremities of cylindrical tubes closely adjacent, eacli of 

 which has the function of secreting wax, and this wax, there- 

 fore, necessarily preserves the form impressed upon it at its 

 origin. It does not necessarily follow that a crenulated 

 margin always carries a fringe; for example, A. hirsuta has 

 deep crenulations but no fringe. 



A curious illustration of my remark just now, that the 

 Aleurodida affect only the under surfaces of leaves, and never 

 (or scarcely ever) the upper surfaces, and therein differ from 

 other Homoptera, has been furnished to me since this paper 

 was vrritten. Mr. C. Musson sent me, from the Kurrajong 

 Hills, in New South Wales, some leaves of Syncarpia lauri- 

 folia which were covered with numbers of very deep pits on 

 the upper surfaces, the other sides being pressed out into con- 

 spicuous elevations. Examining these with a lens, I found in 

 each pit what seemed to be an Aleurodid pupa, looking dor- 

 sally very much like that of A. melicyti. When, however, I 

 extracted one of these, I found that the rudimentary feet and 

 antennae were not enclosed in the pupa-case, but were very dis- 

 tinctly free and active (the ventral surface of the insect being 

 exceedingly convex) ; and on examination, under the micro- 

 scope, no trace appeared of any vasiform orifice. Further, 

 the extremity of each foot was furnished with a fan-shaped 

 pad beneath the two claws. It was clear, therefore, that I 



