460 N. E. McINDOO 
and mosquitoes, and were copied from Hauser, vom Rath, and 
Nagel. The drawings were made at the base of the microscope 
with the aid of a camera lucida. 
THE OLFACTORY PORES 
Before making a study of the anatomy of the organs, called the 
olfactory pores by the writer (’14 a), the distribution and number 
of them were first investigated. 
Disposition of pores in Musca domestica 
Owing to an abundance of material and to the economic im- 
portance of the house fly, the olfactory pores of this insect have 
been studied and drawn in detail, and it is hoped that such work 
will encourage experimentation along practical lines. 
a. Pores on legs. Seven groups of pores lie on each leg and 
the disposition of them is as follows: nos. 1 to 4 on the inner 
surface of the leg (fig. 1) and nos. 5 to 7 on the outer surface; 
nos. 1, 2, and 5 being on the trochanter, nos. 3 and 6 on the femur, 
and nos. 4 and 7 on the tibia. Nos. 1 and 2, consisting of 5 and 
8 pores, respectively, always lie on the anterior margin of the leg, 
while no. 3, composed of 11 pores, lies on the posterior margin. 
Nos. 4 and 7, when present, may lie on either or both margins of 
the leg and the number of pores in each group varies from one to 
three. No. 5, consisting of 3 pores, usually lies near the poste- 
rior margin, while no. 6, composed of 1 pore, lies near the anterior 
margin. 
b. Pores on wings. Six groups and several scattered pores lie 
on each wing and the disposition of them is as follows: Nos. 8 to 
11 and scattered pores a to ¢ lie on the dorsal surface of the wing 
(fig. 2), while nos. 12 and 13 and the seattered pores d and e lie 
on the ventral surface. No. 8, consisting of about 24 pores, lies 
at the proximal end of the propterygium (Pr), while nos. 9 to 13 
lie on the subcostal (Sc) vein in about the positions as indicated 
by the numbers in figure 2. The number of pores‘in each of these 
groups varies slightly, but the average number in each is about as 
follows: no. 9 has 50 pores; no. 10, 12 pores; no. 11, 10 pores; 
