136 TRANSACTIONS OF THE LINNEAN SOCIETY, 
examine the development as a whole, from the commence- 
ment of the changes in the egg up to the final completion of 
the animal, and not suffer ourselves to be misled by the cir- 
cumstance that insects do not all leave the egg in the same 
stage of embryonal development.” 
After quitting the egg, the general opinion of entomolo- 
gists is, that the life may be divided into three periods, each 
marked by a change of skin and an alteration of form. 
Mr. Lubbock, however, wishes to show “that in several 
insects there #8 no such well-marked, threefold division; and 
that in Ephemeride at least the young insect gradually 
attains its perfect condition through a series of more than 
twenty moultings, each accompanied by a slight change of 
form.’ 
He then proceeds to cite instances already observed of ex- 
ceptional cases to the assumed uniformity, and says that we 
shall probably find that there are far more variations from it 
than most people are at present prepared to accept. 
Amongst the Coleoptera are cited the curious and compli- 
cated metamorphoses of Meloc and Sitaris, described by 
Newport and by Fabre. Amongst the Diptera is noted the in- 
teresting case of “‘ Pupipara”’ and Lonchoptera. In the 
Physapoda is noticed the case of Thrips. In the Homoptera 
he has satisfied himself of the existence of at least five well- 
defined stages in Typhocyba. Whilst in Aphis there are at 
any rate more than three. 
“Tf,” he says, “ we now attempt to ascertain the secondary 
laws which regulate the form under which any given family 
of insects is hatched, we shall find that the whole develop- 
ment being, in a certain sense, in all cases the same, the 
rapidity with which the different organs are developed varies 
in different insects; and that the condition at birth depends 
partly on the group to which it belongs, but perhaps still 
more on the manner in which it is to live. 
“Thus those larvee which are internal parasites, whether 
in animals or plants, belong to the vermiform state; and the 
same is the case with those which are intended to live in 
cells, and to depend on their parents for food. On the other 
hand, those larvee which are to burrow in wood have strong 
jaws and somewhat weak thoracic legs; those which are to 
feed on leaves have the thoracic legs more developed.” 
A remarkable instance of this kind of adaptation of organi- 
sation to habits is seen in the case of Melvé and Sitaris. 
among the Coleoptera. ‘The insects of this group are at 
first active, hexapod larvee; but having introduced themselves 
into the cells of Hymenoptera, they undergo a retrograde 
