THE MOUTH-PARTS OF SOME BEETLE LARViE. 
377 
likeness. The feelers are exceptionally long. The little 
creature hides among fragments of stone, keeping its feelers 
in a constant waving motion. On being molested it can move 
rapidly through tlie water. 
All the mouth appendages are somewhat displaced from 
their typical position by a dorsi-ventral flattening of the head 
region. The mouth parts have been already described and 
figured by Rolph ('74, pp. 27-9, pi. i, figs. 25, 27, 31). Our 
descriptions and figures must be regarded as a detailed sup- 
plement to his careful work. The mouth parts are all formed 
of a delicate, almost transparent cuticle, the mandibles being 
more strongly chitinised than the other jaws. 
Labrum and Epipharynx. (PL 35, fig. 10). 
In correlation with the dorsi-ventral flattening of the head- 
region, the labrum is about twice as broad as long. The 
whole head-skeleton is symmetrical in every detail — a very 
curious contrast to the very asymmetrical condition found in 
the allied genus Dascillus. 
The anterior margin of the labrum is straight, and beset 
with stiff spines; its sides are raised into lobes convex 
ventrally, and bearing delicate spines. The epipharynx 
presents a complex series of teeth. Anteriorly occurs a row 
of six small teeth arranged approximately in a semi-circle, 
and enclosed by two transverse ridges connecting the convex 
lobes of the labrum. Behind these teeth there is a finely 
ridged raised area, beneath which protrude two slipper-shaped 
teeth, which almost meet in the middle line. Behind these 
, again are two still stronger teeth, against which the molar 
surfaces of the mandibles work. Lastly, just posterior to these 
teeth there is a peculiar four-sided prominence, the two 
anterior corners of which are grooved and form articulating 
surfaces for the inner mandibular condyle (PI. 35, fig. 10, Co). 
The curious articulation of the mandible with the head 
skeleton is indicated by the dotted outlines in fig. 10. 
The anterior region of the labrum and epipharynx recalls 
