122 Proceedings of Indiana Academy of Science. 
will give excellent preparations, which are strikingly clear, if no air or 
water remain in the insect. 
Another method, simpler and decidedly quicker is to mount the louse 
directly from absolute alcohol into Euparal. Euparal as recommended 
very highly by Lee, is a mounting medium whose index of refraction varies 
to such an extent as compared to that of the cleared louse, that it allows 
very minute structures such as pustulated hairs to be seen very distinctly 
and advantageously. Another advantage in this technique lies in the fact 
that xylol is not needed as a final clearing agent and less shrinkage results 
in the insect. Moreover, the expense of xylol is entirely eliminated. 
Such mounts will allow the internal anatomy to be seen in part. If the 
internal anatomy is not desired particularly a still clearer specimen can 
be obtained. 
If the louse be placed into caustic potash or caustic soda previous to the 
final steps in dehydration, all internal structures that cause some opacity 
will be dissolved. It usually requires from 6 to 12 hours to completely 
clear the specimens after which they should be well washed in water before 
the final dehydration is undertaken or certain colloidal precipitates will 
form later. Moreover, the procedure just described will enable one to 
straighten out all legs. which had been drawn under the body during killing. 
whether directly by alcohol or hot water. They become quite soft in the 
potash and are somewhat easily handled. 
Some precautions are necessary in the final mounting into Euparal in 
order that the air may not enter the legs and abdomen of the louse, and 
cause it to become entirely opaque. To overcome this requires care not to 
expose the specimen to air in removal from the absolute alcohol to the 
mounting medium. If, after some time, such mounts in Euparal develop 
peculiar polygonal crystals, they can be removed by gently heating the slide 
over a flame or in an oven. These crystals are camphor which has erys- 
tallized out and which was one of the solvents of the resin used in making 
Euparal, i. e.—Gum Sandarac. 
The species-determining characters in lice are many and yaried. In the 
main, they constitute the greatest difficulty in the study of lice and require 
considerable attention. 
The nomenclature of anatomical parts of lice in this paper is that followed 
by Kellogg in his New Mallophaga I, (1896). 
The head of a louse may be said to consist of two main parts. The front 
which includes the clypeus, and the large swollen hindpart or occiput. The 
front and occipital regions are usually separated by a groove or fossa in 
which are situated the antennae. This is the antennal fossa. The lateral 
margin of this region is called the temporal margin and the posterior 
margin adjoining and touching the prothorax is the occipital margin. With- 
in this swollen occipital region are found bands running from the base of 
the occipital margin to the inner end of the antennal fossa. These are the 
occipital bands. Those bands running forward, well into the front and 
arising at the antennal fossa are the antennal bands. The broad colored, 
chitinized plate between the antennal bands, is the signature. In some gen- 
era, as Docophorus and Nirmus, there arise at the lateral margin, and ad- 
joining the antennal fosa, certain large movable spine-shaped structures. 
