8 
MEMBRA ClDAE. 
have been, published and clearly defined. This decision obviously will reduce the 
value of many so-called species if known only under what may be designated as 
“ cabinet names.” 
Apposite to this, some remarks may be permitted as to the use I have made of 
the specimens contained in the Natural History Collection in the British Museum at 
South Kensington. 
I understand that the collection of Membracidse, at the date of this monograph, 
remains under Mr. Francis Walker’s arrangement, except so far as this has been 
modified by Dr. Butler. 
The printed works of these authors are of course to be relied on as authoritative, 
whilst other undescribed labelled insects must be considered only as cabinet or 
provisional names. 
In the same way, it will be understood that the labels on specimens in the Hope 
collection at Oxford do not necessarily imply more than the opinion of Professor 
Westwood or others who labelled such insects. The author of this monograph also 
only states his belief, that his descriptions conform to continental or other types, in 
cases where he has not personally examined them. 
EXTERNAL ANATOMY. 
Before commencing the diagnosis of species it will be well to touch shortly on the 
general external anatomy of the Membracidse. It will be the task of the expert 
microscopist to deal with the internal organs, when opportunities offer for investigating 
the tissues in the supple conditions of recent life. 
The integuments of insects are generally composed of three layers. The outer 
one is usually smooth, shining, and apparently structureless. With care it may be 
separated from the others by maceration. 
Mostly it is colourless and semi-transparent, but it may be perforated by small 
holes near the seats of hairs or their follicles. 
Beneath this delicate layer or epidermis, there is a soft stratum, which is the 
location of the brilliant colours seen developed in many Coleoptera and Hemiptera. 
The third and thickest layer constitutes the dense corium, in which the bulbs of 
the hairs are fixed ; the sculpturing and apparent punctuation in the surface of many 
of the Membracidse are chiefly caused by the thinning down of this tough layer. 
This punctuation may be well seen when the pronota of genera like Umbonia, 
Hemiptycha, &c., are viewed by transmitted light under a microscope. 
The remarkable spines of these insects have no bulbous origin, but are hollow 
