PREDACEOUS LARVAI 95 
less pronounced wine-red coloring; the chitinous parts are brown or piceous. 
Certain South American forms of M egarhinus are said to show an iridescence, 
similar to mother-of-pearl. The larva of Bancroftia also show a pronounced 
red color of the body. 
Generally speaking the body of mosquito larve is pale, more or less translu- 
cent. It may be modified within the same species by a great variety of circum- 
stances, such as age, condition of health, food, exposure to light, and the presence 
of internal or external parasitic fungi or bacteria. The trachee usually show 
through the integument as wavy lines of a silvery or golden luster from the air 
contained in them. They become less distinct as the larva with approaching 
maturity grows more opaque. The chitinous parts may be yellow, brown or 
nearly black. Sometimes the head shows darker spots dorsally, characteristically 
arranged. We have seen larve in which the head was entirely yellow, others 
with brown maculations, others entirely dark brown, all belonging to one species. 
ADAPTATION OF THE MOUTH-PARTS OF CULICID LARVA TO THE 
PREDACEOUS HABIT. 
The habit of feeding exclusively upon living organisms, principally upon 
other culicid larve, has arisen several times independently among the Culicids. 
The mouth-parts have been correspondingly modified in every case that the habit 
has been developed. It so happens that the organ which has been modified for 
prehension differs in the several groups. The Corethrine are all predaceous 
and seize their prey with the antenne. These organs are consequently modified 
for this special purpose, differing in the several genera. In these forms the 
mandibles have the toothed parts well developed but the hair fringes undevel- 
oped, being confined to a few filaments. The maxille in all the forms known to 
us, Hucorethra, Corethrella, Corethra and Chaoborus, are progressively reduced, 
being slight rudiments only in the latter two genera. This is a special modifica- 
tion in this line of descent and does not represent the condition in the general- 
ized culicid stock. No predaceous form will be found in a primitive condition 
as the habit is secondarily acquired and accompanied by special modification. 
The most generalized condition of the culicid larva is found in Diza. This 
larva is a vegetable feeder with mouth-brushes on the labrum and a coarse hair- 
fringe on the mandibles. It is a surface feeder. The mandibles are dentate on 
the inner side toward the base. The maxille are quadrate and furnished with a 
long functional palpus, comparable to the antenne in shape and size. From 
such a form the culicid series is derived. The lowest mosquitoes, Anopheles, are 
still surface feeders, retaining square maxilla, the palpi of which, though much 
reduced, are still comparatively large. The square maxille may be regarded 
essentially as organs of mastication. They are modified in the higher forms, 
whose manner of feeding has become more refined, into a conical or pointed 
shape with papille and hairs. There is, however, a tendency to the reappearance 
of the square maxilla in the predaceous genera, in adaptation to the new habit 
which requires more mastication. Throughout the Culicid series there is a 
progressive degeneration of the maxillary palpi, whether the predaceous habit 
