192 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY.' 
The Malpighian tubules pass from the larva to the imago without 
visible change. This absence of metamorphosis appears to be the 
rule for these tubules in the Nematocerous Diptera, if observations 
on Simulium, Chironomus, and Psychoda (Vaney, : 02) added to 
those for Culex, give a sufficient basis for generalization. 
.Notes on the metamorphosis. — The organs of Culex outside of 
the alimentary canal undergo a metamorphosis as simple in grade as 
that of the mouthparts or alimentary canal. A few points with 
respect to these organs may be noted. The dermis of the head 
and the body is passed directly over to the imago. The muscles of 
the thorax and abdomen also are seemingly not involved in any 
alterations. The wing and leg muscles are new with the pupa, the 
rudiments of the former being present beneath the hypodermis of 
the dorsum of the thorax during the last larval instar. My obser¬ 
vations on the fat bod} 7 accord with those of Vaney. “In the 
lower Diptera (Culex, Simulia, Chironomus) the fat elements are 
maintained in their integrity from the larva to the adult.” In the 
fat body dorsad of the nerve cord in the abdomen, there can be 
noted during the pupal stage scattered cells which resemble leuco¬ 
cytes more than other cells of the body. These do not, however, 
appear to function in any manner. 
The eyes of the larva form part of the compound e} r es of the 
perfect insect. Hurst (’ 90 ) has given a good account of the evolu¬ 
tion of the imaginal eye, which “consists in the addition of new 
elements at the edge [of the larval eye] which arise by direct modi¬ 
fication of the .... epidermis around the margin of the eye, epider¬ 
mis whose last function was to secrete the pupal cuticle.” He notes 
that “corneal facets are never formed in the pupal cuticle ” and that 
the ocellus of the larva is inconspicuous in the adult. I find that this 
ocellus degenerates during the papa stage. The cells become vacu¬ 
olated, the pigment agglomerates, and the whole structure sinks 
beneath the dermis. In the perfect insect each ocellus is hardly 
more than a small mass of black pigment at the rear of the com¬ 
pound eye. 
Both Culex and Anopheles have a pair of rudimentary ocelli which 
do not seem to have been described. They are situated on the 
vertex of the head, caudad and mesad of the bases of the antennae. 
Each consists of a plate of enlarged dermal cells, lying immediately 
over a small ganglionic mass of spindle-shaped cells. A fine nerve 
