PASSEEINI. 
65 
at tlie same time given to the polyphagous species.^ 
He remarks that, if we know the ordinary food-plant 
of an Aphis, we may be able with better success to ap- 
prehend such minute visible characters as are indi- 
cated by the diagnosis. In this way additional weight, 
for or against, may be given to indecisive features. After 
pointing out the several researches of Guinani and 
Barelli, and the work of Gene, of Turin, on noxious 
insects, Passerini claims credit for Italy, inasmuch as 
he says she furnished the first platform for opera- 
tion, from which the march of inquiry has by rapid 
strides proceeded through Germany, England, and 
France. 
Probably it will be thought that in some cases 
Passerini has too severely curtailed Koch’s list of 
Aphides, nevertheless the succinct descriptions fur- 
nished by his tables form valuable additions to Kalten- 
bach’s and Koch’s monographs. Perhaps these three 
systematic text-books are the best which have yet 
appeared on the subject. 
It would be useless merely to enumerate the names 
of authors who have with more or less success 
published papers on Aphides. Some, like Riley in 
America, have shown that many species common in 
Europe are also scattered over parts of Korth America; 
whilst other authors, like Signoret in France, have 
proposed classifications based on new characters ; but 
having briefly adverted to the more important works 
of naturalists who chiefly have devoted their attention 
to the specific characters, I proceed to mention some of 
those who have pushed their researches into the more 
difficult departments of minute anatomy and embryonic 
development. 
First in order amongst British anatomists may be 
mentioned George Kewport,t who in 1846 communi- 
cated to the Linnsean Society of London a short paper 
* G. Passerini, ‘ Flora degli Afidi Italiani/ 
t G. Newport, ‘ Linn. Trans.,’ vol. xx, p. 281, “ On the Generation of 
Aphides.” 
5 
