162 
The Ohio Naturalist. 
[Vol. VII, No. 8, 
differ considerably from the general type of insects’ eyes in con¬ 
sisting of a smooth elevated area with very sharp, definite out¬ 
line; this area being termed the eye spot. Arranged in two or 
more distinct rows on each eyespot are the true eyes or ocelli. 
These are entirely separate and function as do the simple ocelli 
in the higher insects. Eight ocelli are found in each eye spot, 
varying in size in the same species. 
The Antennae. Immediately in front of the eyes are the 
long, slender antennae, the terminal segment of which is but little 
longer than the basal segment, and conical in shape. Both the 
third and fourth joints bearing whorls of hairs and one or both 
are often annulated, as in marmoratus , while the third joint is 
composed of sixteen sub-joints; in unicolor the third joint has 
seven or eight sub-joints, and the terminal segment about ten; 
and in olympius the terminal joint has seven sub-joints. As to 
the other sepcies we can not say, the descriptions being too brief. 
The Mouth Parts, are more or less withdrawn within the 
head and are intermediate between the true mandibular insects, 
and those with mouth parts adapted for sucking. The upper 
and lower lip appear as small, flattened, almost scale-like struc¬ 
tures, while only the tip of the maxillae and mandibles are visible. 
These organs are much elongated and together with the hypo- 
pharynx may be used to rasp off particles of decayed vegetation 
upon which the animal feeds. 
The Thorax, as in all insects, consists of three segments, pro, 
meso, and meta thorax, each bearing a pair of legs. In this genus 
the segments of the thorax, especially the first one is greatly 
reduced and partially covered by the protrusion of the second seg¬ 
ment of the thorax. As a usual thing the legs are long, 
slender, and covered with hairs or spines. Two claws are always 
present, a larger and a smaller one; the concave edges facing one 
another, and the larger one curved around the end of the smaller 
one. Small teeth may be found in various numbers on these 
claws; the larger claw in texensis and marmoratus bearing three 
teeth, while in the remainder of the species it has two, except in 
novoeboracensis of which we have no knowledge. The smaller 
claw is found either dilated, as in texensis, bearing one tooth as in 
maculosus and unicolor, or hairy as in olympius and purpurescens. 
Tenant hairs are mentioned only for purpurescens. 
The Abdomen, as before stated, consists of six segments, 
which with the exception of the terminal one are fused, and from 
the dorsal side can not be distinguished. On this account the 
abdomen presents a smooth even surface, sparselv covered with 
hairs, and never bearing scales, as is gommon with so many 
Thysanura. Packard’s marmoratus is'mentioned as having two 
pale, smooth tubercles on each side of the basal, abdominal seg¬ 
ment and MacGillvray’s purpurescens an anal tubercle; however, 
