i62 The Ohio Naturalist. [Vol. VII, No. 8, 



differ considerably from the general type of insects' e_ves in con- 

 sisting of a smooth elevated area with very sharp, definite out- 

 line; this area being termed the eye spot. An-anged 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 eve 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 ©ften annul ated, 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 olympins the terminal joint has seven sub-joints. As to 

 the other sepcies we can not sa}^ 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The Mouth Parts, are more or less withdrawn within the 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 wnth 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 hvpo- 

 pharynx may be used to rasp off particles of decayed vegetation 

 upon which the aniftial feeds. 



The Thorax, as in all insects, consists of three segments, pro, 

 m2so, and meta thorax, each bearing a pair of legs. In this genus 

 the segments of the thorax, especial!}^ 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 larg^er 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 Abdo.men, 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 distinguislied. On this account the 

 abdomen presents a smooth even surface, sparselv covered with 

 hairs, and ne\'er bearing scales, as is common 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, 



