110 
NEUROPTERA. 
terrestrial ancestor of the Planipennia . Quite possibly this branch 
leads on from an ancestor of the present Trichoptera to the Lepidoptera , 
the ancestor of Micropteryx and of Trichoptera being the same and thus 
giving the point of contact. 
Mallophaga.— Biting Lice . 
Small wingless insects] nearly all parasitic on birds. They have biting 
mouthparts and the body is flattened , the head 
often large and broad. 
The Mallophaga or Bird-lice are sometimes confused with the Pedi- 
culidce (Head-lice and body-lice). Although both are parasitic on warm¬ 
blooded animals and have somewhat the same appearance, they are 
quite distinct, the Pediculidce being sucking insects, allied to Hemiptera, 
while the Mallophaga have well-developed biting mouthparts and never 
suck, living on the dry skin, scurf, and feathers of their hosts. Their 
relationship to other insects is doubtful, and Kellogg, who has mono¬ 
graphed the group (Genera In sec to rum Fasc. 66) reckons them as a 
distinct Order. Mallophaga spend their whole life on the host, and soon 
die when removed or when the body of the host becomes cold in death. 
Observations on their life-histories are for this reason difficult, and little 
is known except that the metamorphosis is incomplete. Kellogg puts 
the known species at over a thousand, and a large number of these are 
restricted to one definite species of bird ; others are found on several 
different birds, but usually these birds either are accustomed to associate 
one with another in flocks, or belong to closely related species, though 
these related species may occur only in widely separated parts of the 
world. 
Kellogg explains this curious fact by reference to the sedentary 
mode of life of the insects, which prevents their spreading from bird to 
bird except by actual contact. He supposes that the species of Mallo¬ 
phaga have remained unchanged since the remote periods when many 
different species of birds, (now settled in different parts of the globe and 
separated from their near relations,) had not yet diverged or evolved 
from their common ancestral species. Those ancient bird-lice which 
infested the ancestral bird continued to infest the ancestral bird’s des¬ 
cendants: even though these descendants in time diverged into several 
