562 Wisconsin Academy of Sciences, Arts, and Letters. 
Labium and labial lobes. (PL XXXI, Pig. 16; PL 
XXXIV, Pig. 2). The anterior part of the sub-mentum is dis¬ 
tinctly paired. The mentum is indented in the middle, and the 
sides of this indentation are fringed with fine hairs. The 
galea and 1 acini a are fairly distinct, the lacinia being less 
thickly clothed Avith hairs and Avith its distal part wholly mem¬ 
branous and tAvisted. Its proximal part is connected with the 
hypopharynx, which is here triangular and again bears peculiar 
hairs, principally on its outside edges. 
Choeridium histeroides Web. 
The epipharynx is of the usual type, but the club-shaped, 
chitinized median thickening is here relatively broad and less 
prominent, Avidening posteriorly. We here have the first step 
toward a disappearance of this thickening. 
Labial lobes and hypopharynx (PI. XXXI, Pig. 17). The 
inner lobe is membranous and fringed Avith strong, pointed 
hairs, the outer lobe for the greater part chitinized. Where 
the lobes join the hypopharynx, their dorsal surface is sparsely 
covered A\dth numerous short, conical projections; where they 
meet in the median line they are furnished with three long, 
blade-shaped hairs, Avhich here, however, are firmly chitinized, 
and which may be considered intermediate between the sense- 
hairs as found in other forms and the teeth which we find in 
Copris. The hypopharynx itself is quadrangular and clothed 
with moderately long, fine hairs. 
Pleurophorus caesus Panz. 
Epipharynx (Pig. 18). Though still presenting the gen¬ 
eral appearance found throughout this group, the epipharynx 
shows some important modifications in structure. The hairs 
on the incurved lateral margin are broader, stronger and more 
brush-like. The median club-shaped thickened area with its 
sense-hairs has entirely disappeared, the field between the lateral 
areas being furnished instead with a comparatively few short, 
conical projections. 
Mandibles (Fig. 19). These show a more distinct chitiniza- 
tion at the lateral and distal margin. The fringe of hairs at 
the end of the galea has disappeared, the whole mandible being 
more compact with its tip no longer membranous. The molar 
