400 
MR. J. G. H. FKEW : MOUl'HOLOGY OF THE HEAD CAPStlLi; 
and near tlie dorsal portions o£ the ai-ms of the epicranial suture " (Peterson, 
p. 26). According to Oomstock and Kochi (1, p. 41), "Each dorsal arm ol: 
the tentorium arises from the side of the bodj^ of the tentorium between the 
a.nterior and posterior arms, and extends either to the front or to the miirgin 
of the antennal sclerites." 
If one examines the tentorium of Chlorops li'is seen to consist of three 
distinct chitinous rods on each side (figs. 1 and 2). One rod on each side 
(p.a.) arises at the side of the occipital foramen and passes forwards along 
the ventral surface of the head capsule ending at the point niarlced X in 
figure 1, at the ventral corner of the ridge which forms the lateral 
boundary of the oral depression in which the proboscis lies when retracted. 
These two rods are obviousl}^ the posterior arms of the tentorium ; the question 
Fig. 1. 
Fig. 2. 
Caudal aspect of Head Capsule. 
Cephalic aspect of Head Capsule. 
of the position of the body of the tentorium is dealt with in connection with 
the morphology of the caudal aspect of the head. From the point X a second 
chitinous bar {a.a.) runs along each lateral margin of the oral depression 
ending at the point marked Y in the figure. This bar is a thickening of the 
mesial wall of a shallow slit-like depression (s.), which extends along each 
lateral margin of the oral depression. From the point Y a third bar (d.a.) 
on each side extends dorsally along the anterior suface of the head ; the 
dorsal end of each of these bars is strongly curved and almost encloses 
the antennal base of its side in the manner shown in the figure. All three 
arms of the tentorium are fused along their entire length with the head 
capsule. The dorsal margin of the oral depression is marked by a strong 
bar {p.), which unites the two halves of the tentorium. 
