lxix 
The interesting problem of what is the true ancestry of Insects, 
and which line was taken in their progress of development, is one 
which has of late been much discussed. Sir John Lubbock, 
following Brauer, indicates Campodea, a curious larval form, 
allied to Thysanura and Collembola, as the nearest existing 
representative to the ancestral type of the Insecta. The mouth 
of these insects is neither truly suctorial nor mandibulate, and 
thus affords a starting point for special modification in both direc- 
tions. The larve and pupe of the higher insects are certainly not 
mere lower stages in the progressive development of the imago, as 
was once supposed, but are highly specialized forms, which, 
during a long series of ages, have diverged so as to become 
adapted to widely different modes of life. They are not likely, 
therefore, to represent ancestral types, which must rather be 
looked for in certain exceptional developmental forms, such as 
the hexapod larve of Meloé for example. Dr. Packard en- 
deavoured, nearly two years ago, to carry the solution of the 
problem one step further back. He believes that the Insecta and 
Crustacea have been independently evolved from some low 
annulate animals; the Insecta passing through a rudimental 
form to which he gives the name Leptus, analogous to the well- 
known Nauplius form of Crustacea. The Myriapods he believes to 
have descended from a Leptiform animal, something like the 
young of Pauropus ;—the Hexapods from one more resembling 
the young of Stylops and Meloé, and certain low Orthopterous 
and Neuropterous larve. Dr. Anton Dohrn is now engaged in a 
systematic study of this subject, taking, as his basis, the maxim 
that the development of the individual is a short and incomplete 
statement of the development of the race; and working out the 
embryology of as many types as possible, so as to discover how 
far their earliest stages agree or disagree. He has hitherto 
principally occupied himself with the Crustacea, but seems 
inclined to revive the old idea of the possibility of finding 
homologies between the Annulose and Vertebrate types. The 
Russian anatomist Kowalewsky holds somewhat similar views, 
but they seem to be founded on the supposed histological identity 
of certain internal organs and tissues, rather than on any ac- 
curately determined homologies in the great structural features 
of each sub-kingdom. 
Amid all the discussions to which this subject has given rise, it 
