410 Wisconsin Academy of Sciences, Arts, and Letters. 
creasing in early summer as the oxygen goes out, and increas¬ 
ing with the increase of the oxygen content of the hypolimnion 
in early fall. 
A dimorphism in size of the larvae, which was at .first sup¬ 
posed to indicate a two-year cycle, was later found to be a sex¬ 
ual difference, the larger larvae being females. Female larvae 
may attain a size of 5 cm., while males rarely exceed 3-3.5 cm. 
This species forms a very conspicuous item of fish food, es¬ 
pecially during the winter. 
In connection with this species it seems appropriate to test 
out Miall’s dictum, ‘Hhat only such Chironomus larvae as live 
at the bottom and burrow in the mud possess the red hemo¬ 
globin. Those which live at or near the surface have colorless 
blood.” As far as Chironomus tentans is concerned, the red 
color is characteristic of the larva no matter where it occurs,— 
in the bottom of the lake, pond, or horse-trough. Conversely, 
Protenthes choreus with which it is associated in the lake, 
shows only occasionally a slight suffusion of pink, no matter 
where it may be found; usually the larvae are of a cream or 
pale green color, with the fat body showing through the epi¬ 
dermis. 
In general, I have found so much variation as to the color 
of the larvae of the various species in identical surroundings 
that it is obvious that no fixed rule can be laid down as to col¬ 
oration. There is no intensification of color parallel with the 
increase in depth, such as Miall suggested. I have taken red 
specimens of C. lobiferus, digitatus, fulviventris, etc., from 
depths varying from 0.2 to 6 ni.; while pale specimens of 
the same species were found at precisely the same depths (see 
discussion of color varieties under C. lobiferus). In fact, at 
any given spot on the shore one may find specimens of these 
species colored a brilliant scarlet, while at a depth of one meter 
or five meters the same species may be pale, or vice versa. 
What I wish to emphasize is the absolute lack of any correla¬ 
tion of intensification of color and of oxygen supply. Need¬ 
ham (1903) called attention to the fact that the young of the 
red species when hatched from the egg are pale, never red. 
Chironomus digitatus Malloch; Chironomus fulviventris 
Johannsen; Chironomus lobiferus Say. 
These three species are littoral forms of wide distribution. 
C. digitatus is of special interest in that it is sand loving form 
