554 Wisconsin Academy of Sciences, Arts, and Letters . 
count of this it has been entirely overlooked by some authors, 
who have applied the name “mentum” to the sub-mentum, and 
called the true mentum the “hypoglottis” (Leconte and Horn, 
6 ). The remaining parts of the labium except the palpi are 
called the ligula by Comstock (1), and this author divides it 
into a central part, the glossa, and “two parts, usually small 
membranous projections, one on each side of the base of the 
glossa, the paraglossae” 
There is great confusion concerning the homologies of the 
parts of the labium, some contending that “the sub-mentum 
and the mentum, or the mentum when no sub-mentum is dif¬ 
ferentiated (with the gula when present), appear to be col¬ 
lectively homologous with the cardines of the first maxillae, 
together with the palpifers and stipites” (7). The lobes of 
the lahium are generally admitted to be the homologues of the 
galea and lacinia of the maxilla. Otokar Xadic (3) consid¬ 
ers the sub-mentum and mentum together as the sub-mentum, 
and thinks that the mentum proper, with its appendages, the 
palpigers (squamae palpigerae), the glossae and the para¬ 
glossae, has grown inward over the sub-mentum. I am in¬ 
clined to accept his view for some cases; the correctness of 
this notion I hope to show subsequently. 
The hypopharynx arises as a fold from the floor of the 
mouth and is an unpaired membranous structure like the epi- 
pharvnx. It is continuous with and forms the anterior part 
or fold of the base of the second maxilla. It does not seem to 
represent a pair of appendages. Kolbe (5) considers the 
hypopharynx a third pair of maxillae, calling it the endo- 
labium, and claims that it can be recognized as such in Hemi- 
merus talpoides (a roach-like form from West Africa), and 
that it bears palpi. He further claims that the hypopharynx 
originates as a third pair of jaws from a special primitive 
head-segment, but says: “Dieses Organ ist bei den bisher un- 
tersuchten Embryonen selbst nicht in elementarer Form gese- 
hen, wahrencl doch die zu Mandibeln, Maxillen und zur Dnter- 
lippe sich ausbildenden Anhange in den meisten Fallen deut- 
lich angelegt sind;” and further: “Indes muss es befremden, 
