196 
Psyche 
[Aug. -Oct. 
so perfectly constructed that it has been able to defy the ravages 
of time and changing conditions, and the fact that the “ change- 
less conservatism” of roaches has resulted in their retaining many 
features characteristic of the types ancestral to higher insects, 
makes their study doubly interesting. 
In carrying out this study, I had hoped to include all of the 
main features of the gross external anatomy of the roach in a sin- 
gle paper; but as the work progressed, it soon became apparent 
that roaches present so many features of morphological interest 
that it would require too many figures and plates to illustrate the 
structure of the entire body adequately in a single article. I would 
therefore present herewith the principal features of the head and 
abdomen alone, leaving for a subsequent paper the discussion of 
the thorax and its appendages. The American roach, Peri- 
planet americana , was chosen to illustrate the anatomy of atypi- 
cal roach because of its large size and relative abundance which 
render it exceptional^ suitable for such a study. Specimens 
preserved in alcohol may be readily obtained from Southern sup- 
ply houses for approximately five dollars a hundred, and the study 
of the external anatomy of these insects is well suited to serve 
as an introduction to the study of the external anatomy of insects 
in general for students beginning the study of Entomology. A bin- 
ocular dissecting microscope is absolutely essential for examining 
the external anatomy of the specimens, which should be studied 
immersed under alcohol or water, and the field should be illumi- 
nated by means of a powerful lamp provided with a bulls-eye 
condenser. 
Seen under the binocular, the head of the roach (Fig. 5) is a 
beautiful object, “clean-cut,” and smoothly polished. The upper 
lip or labrum Ir is emarginate anteriorly (i. e. there is a “nick” or 
emargination em in its anterior margin). Behind the labrum is 
a non-pigmented area ac or anteclypeus followed by a more 
heavily chitinized and pigmented area eps called the post- 
clypeus or epistoma. The areas ac and eps comprise the clypeus, 
which extends from the labral, or clypeolabral, suture (along 
which the labrum is hinged the clypeus) to the frontal pits fp, 
which are the external manifestations of certain invginations 
forming the anterior arms of the tentorium presently to be 
