144 
Psyche 
[September 
to determine the actual number of body segments. It is 
evident enough that there are eight segments which com- 
pose the posterior widened portion. Anterior to these eight 
there are several more, probably three, which make up the 
narrowed snout-like anterior portion of the body. 
On each side and above the mouth there is a short, broad, 
pointed projection (figs. 7, 8, p). These structures prob- 
ably bear sense organs. The mouth (m) is immediately 
below and between these cephalic projections and is shown 
in figure 7. At the base of these projecting structures on 
the dorsal aspect (figs. 7, 8, n) is a slender transverse 
sclerotized bar. On the ventral aspect also is found a 
sclerotized structure which extends transversely, surround- 
ing the base of the projections, and widens mesally to form 
an inverted V (fig. 7, o). 
The cephalo-pharyngeal skeleton is withdrawn into the 
anterior end of the body (fig. 8) and is composed of several 
principal sclerites. The most anterior are the oral hooks 
(figs. 2, 3, oh). These are simply curved and bear on the 
ventro-caudal surface a tooth. This basal tooth is promi- 
nent and extends cephalo-ventrad. On the mesal margin 
and well toward the cephalic end of the right oral hook is 
a small tooth (fig. 3, r), which projects meso-caudad. The 
left oral hook possesses no such tooth. The intermediate 
sclerite which is present in the cephalo-pharyngeal skeleton 
of many of the higher Diptera is absent. The oral hooks 
articulate basally with the large basal or pharyngeal sclerite 
(figs. 2, 3, phs). The latter is formed of two lateral, verti- 
cal plates which are joined ventrally to form a trough which 
supports the pharynx. The pharyngeal sclerite is more 
weakly sclerotized than the remaining parts of the cephalo- 
pharyngeal skeleton. The sclerotization is strongest in the 
region of the point of union of the two plates and decreases 
as the dorsal and caudal portions are approached. The 
shape of these plates is rather difficult to describe but is 
shown in figure 2. At the ventro-cephalic end these plates 
are connected by a sclerotized cross-bar (s). Caudad of 
this cross-bar is a quadrangular opening in the trough 
formed by the pharyngeal sclerite. More or less joined to 
each lateral plate of the pharyngeal sclerite at its ventro- 
