214 
Psyche 
[Aug.-Oct. 
cerning their function, or that of the pointed process acl or of 
the small plate bu which bears a short recurved hook-like fold 
or process. The large supporting arches labelled ana and bar in 
Fig. 23 and 25 serve to strengthen the lobes and processes, and 
also furnish points of attachment for muscles, as do the internal 
projections and processes labelled enl and epr in Fig. 25. 
The interpretation of the homologies of the above-mentioned 
parts has not been thoroughly worked out, although Walker, 
1922, suggests that the structures labelled tt, ser, etc., represent 
the parameres of other insects. Walker, however, applies the 
designation parameres to entirely different structures in the Ap- 
terygota and Pterygota, and different investigators apply the 
term to so many different structures in different insects, that it 
is practically impossible to say what is meant by the term para- 
meres. If we restrict the designation parameres to the second 
arily-formed outgrowths and chitinizations of the membrane 
about the intromittent organ, the term parameres might well 
be applied to the above-mentioned structures in the roach. The 
lobes op etc., of Fig. 25, however, are probably formed in the mem- 
brane about the intromittent organ also, and it is necessary to 
find some other method of differentiating the parameres from 
the other structures formed in this region. Walker refers to the 
lobe pel as the penis, but I think it is preferable to restrict the 
designation penis to the structure labelled pe in Fig. 25, since I 
think it very probable that the lobe pel corresponds (partly, at 
any rate) to the chitinized parts about the true penis called the 
adeagus in other insects. It is quite evident, however, that the 
whole subject of the homologies of the genitalic parts of male 
insects should be more throughly studied from the standpoint of 
comparative anatomy, development, etc., with a view to deter- 
ming the true interpretation of the parts in these structures 
which are so much used in systematic entomology. 
In the immature roach shown in Fig. 22, the chitinous pro- 
jections, etc., of the adult insect are not yet developed, and the 
membranous lobes shown in Fig. 22 represent the undeveloped 
condition of the more complicated genitalia shown in Fig. 25. 
In capturing the specimen shown in Fig. 22, the insect was 
rather tightly squeezed, and the pressure apparently caused 
