88 
The Ohio Naturalist. 
[Vol. XIII, No. 5, 
nearly straight. From its posterior end arises the tail-like 
respiratory appendage (Fig. 145, c) which is usually curved 
anteriorly above or around the bod)'. It is commonly shortened 
to a length of 8 to 10 mm. of which the basal segment often forms 
about two-thirds, the terminal one .usually being second in length. 
The tracheal tubes from these appendages soon become constricted 
off a short distance within the main body of the puparium and 
are not functional during most of the pupal stage. 
At the approach of pupation there appears under the larval 
skin, about one segment back of the anterior or larval respiratory 
cornua, (Fig. 131, b; 145, a), a pair of rounded darkened areas. 
These soon become elevated to a length of about 2 mm.; their 
diameter being about 0.25 mm., rather uniform to near the tip 
where they round off (Fig. 145, b). They are provided on the 
distal three-fourths or four-fifths of their length with several 
hundred, short, rounded tubercles (Fig. 147). These tubercles are 
somewhat collected into groups, and, especially along the anterior- 
median surface, are absent over a longitudinal stripe. When 
highly magnified each tubercle is seen to be ornamented on the 
tip with about S or 9 radial elevations, which I take it are the 
spiracles. (Fig. 148). The elevations as a whole are called the 
pupal respiratory cornua. Internally to the puparium they 
continue as large trachea, which attach to the dorsal part of the 
prothoracic segment of the developing nymph (Fig. 14(5, a). 
There is thus quite clearly a special provision for pupal respiration. 
These might be considered homologous with the prothoracic 
spiracles of the adult fly; and since they penetrate the puparium 
about one segment back of the anterior larval respiratory cornua, 
it might seem improper to consider the larval segment which 
bears the latter the prothoracic. Nevertheless, it does not seem to 
me that the point at which these pupal cornua emerge should be 
considered of much significance. The larval skin at this time is 
much distorted out of its normal shape by contraction and 
inflation and it would not seem that segmental homology could 
longer hold. 
The larval respiratory cornua (Fig. 145, a) become fixed at a 
length of about 0.75 mm. their diameter being slightly less than 
that of the pupal cornua just described. They are recurved 
slightly to a sharp point. The sub-circular group of rounded lobes 
at its tip in the larva (Fig. 132), become obscure in this stage. 
Internally the trachea from these cornua are constricted off and 
have no connection with the pupa, at least in its more advanced 
stages. 
The buccal cavity, antennas, etc., are retracted within the 
puparium a short distance back of the anterior end where the 
dorsal elevation begins. Internally the oesophageal framework is 
flattened against the ventral wall of the puparium from which the 
