CHLOEON (EPHEMERA) DIMIDIATUM. 63 
shall probably find that there are far more variations than we are most of us, at present, 
prepared to accept. 
Among Coleoptera, we owe principally to Newport and Fabre a knowledge of the 
curious and complicated metamorphoses through which Meloë and Sitaris arrive at 
maturity. 
Among the Diptera, the interesting case of the * Pupipara" has long been known; 
and I have also shown * that the curious larva of Lonchoptera turns into a simple grub 
inside the east skin, before it developes the rudimentary, or at least imperfect, organs 
which are characteristic of the pupa. 
The metamorphoses of the Physapoda (Thrips) are thus described by Mr. Haliday + :— 
** Metamorphosis incompleta, per duas ætates intermedias progrediens, scilicet, propupa 
et pupa, asitophaga, tardigrada. Larva oculorum lenticulis paucis dissitis." 
M. Yersin has described several stages in the development of Gryllus campestris. 
Among the Homoptera, I have satisfied myself that in Typhlocyba, a genus of Cercopidze, 
there are at least five well-defined stages, while in Aphis also there are more than three. 
Among the Neuroptera also, the genus Psocus seems to pass through at least four 
conditions. 
No doubt this list might easily be augmented ; but it is at least sufficient to show that 
the presence of three stages, and three stages only, is far from being so generally true of 
insects as has been supposed. 
If now we 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 development 
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 larvze 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, larvae 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. 
Now the Hymenoptera, as a general rule, belong to the first category: the larvze of the 
Ichneumons, &c., which live in animals,—those of the Cynipide, which inhabit galls,— 
and those of Ants, Bees, Wasps, &c., which are fed by their parents, are all fleshy, apodal 
grubs. On the other hand, the larye of Sirex, which are wood-burrowers, quit the 
type which is common to the majority of the order, and remain in the egg until 
they have developed small thoracie legs. Again, the larvæ of the Tenthredinidz, 
which feed upon leaves, closely resemble the caterpillars of Lepidoptera, even to the 
presence of abdominal prolegs. There is, however, some little variety in this respect, some 
species having eleven pairs, some ten, some nine, while the genus Lyda has only the three 
thoracic pairs. note 
Perhaps, however, the most remarkable cases of all are the genera 116106 and Sitaris 
among the Coleoptera. The insects of this group are at first active hexapod larvz ; but 
ological Transactions, 1862. + British Museum Catalogue of Homopterous Pc p. 1094,‏ د چ 
K 
