68 ENTOMOLOGICAL SOCIETY 
perfectly naked. They may approach close together or be widely 
separated ; Chiloneurus and Caratomus being two extremes in 
this respect. They vary in color from bright coral red, through 
reddish-brown and slate to black. The red shades are preserved 
in balsam-mounted specimens, but are lost in pinned specimens 
after death. With certain groups of genera the eyes invariably 
sink in and present a concave centre after death, while with 
others they always preserve their normal form. This sinking 
in also extends to the other parts of the head, very seldom to 
the other parts of the body, so that in these genera, notably in 
the Tetrastichintz, the head characters have to be studied from 
fresh specimens. 
The ocelli are comparatively large, and are placed in the form 
of a triangle which may be very acute or very obtuse angled, 
depending to some extent upon the degree of separation of the 
eyes. They vary in color as do the true eyes. Sometimes they 
are small and so hidden by the pubescence of the head as to be 
almost indistinguishable. In the anomalous group Aogonidcz of 
Walker there is much variation in the presence or absence of 
eyes and ocelli. Eupristina, for instance, has neither eyes nor 
ocelli in the male, while the female has large oval eyes, but in- 
conspicuous ocelli. In Walker ella the ocelli are absent and the 
eyes are small. This is also the case with Sycoscaptella and 
Otites ella. 
The mandibles are usually strongly developed, although not so 
much so as with some of the Proctotrupidae. They are quite 
strongly convex dorsally and are often transversely impressed at 
base. At the apex, and along the median line when closed, they 
are furnished with from two to four teeth. The teeth of the two 
opposite mandibles often differ in number, the right having four 
and the left three. With the Macrocentri the mandibles are 
usually stronger and with more teeth than with the Microcentri, 
in which group they are seldom more than bi-dentate. The 
maxillce are small and consist almost entirely of stipes. The 
galea is imperceptible in the genera examined, and the lacinia 
is simple with almost imperceptible teeth. The maxillary palpi 
are usually 4~jointed, but may be ^-jointed. The labial palpi 
are 3-jointed with the higher forms, but with the lower they are 
rudimentary. 
