314 Afinals Entomological Society of America [Vol. XV, 



3, 28) and in Apterobittacus (Figs. 5, 29), the lateral ocelli (lo) are 

 situated distinctly dorsad of the compound eyes, whereas they are 

 mesad of the latter in the other genera where they are present. The 

 ocelli are located on convex areas in Panorpodes (Fig. 1) and Panorpa 

 (Fig. 10) and are close to each other in Panorpa. The median ocellus 

 (mo) in all cases is slightly smaller than either of the lateral ocelli. 



As stated previously, Hine (1901) divided the genera of the Pan- 

 orpidae into two groups, those with ocelli in one group and those without 

 in another. Merope and Boreus were placed in the first group and 

 Bittacus, Panorpa and Panorpodes in the other. In his monograph, 

 as already referred to, Esben-Petersen (1921) divides the Mecoptera 

 into five families, giving as one of the characteristics of the family 

 Boreidae to which Boreus belongs, the absence of ocelli. I found the 

 normal number of ocelli present in the species of Boreus that I studied. 

 The ocelli, however, were small and overshadowed by the black color 

 and shiny appearance of the head, black with a bluish tinge. This is 

 probably the reason why the ocelli in Boreus have been overlooked 

 by previous workers. A few minutes' treatment of the head with a 

 five per cent solution of potassium hydroxide will reveal the ocelli as 

 circular, white opaque bodies. Each lateral ocellus is located near 

 the dorso-mesal margin of a compound eye and the median ocellus 

 between the antacorias (an). Judged from the location of the ocelli, 

 Boreus is more specialized than any of the other genera. 



There is a pair of depressions on the cephalic aspect of the head 

 ventro-m'esad of the compound eyes. These depressions are known as 

 the pretentorinae (pn), which mark the point of invagination of the 

 pretentoria (pt, Figs. 37, 38, 39, 40). In Panorpodes, Panorpa and 

 Boreus, the pretentorinae are situated directly ventrad of the antacoriae 

 (an), while they are distant from the latter in Bittacus, Apterobittacus 

 and Merope; they are, in these last three genera, near the ventro-mesal 

 margin of the compound eyes and distinctly more so in Bittacus where 

 they nearly touch the margin of the eyes. 



In specialized insects, the pretentorinae are not fixed in location. 

 They may migrate away from the precoilae (pr) but are usually located 

 on or near the epicranial arms. In the Orthoptera, the pretentorinae 

 are located immediately dorsad of each precoilce and are apparently 

 distant from the epicranial arms. In the Mecoptera, they are isolated 

 from the precoilae and are markedly so in Panorpa and Boreus, owing 

 to the great elongation of the fronto-clypeus. 



The precoilae (pr) in which the mandibles are articulated on the 

 cephalic aspect are distinct in the Mecoptera. Each precoila is located 

 at the ventro4ateral angle of the fronto-clypeus. In generalized 

 insects, each precoila is situated at the caudo-lateral or dorso-lateral 

 angle of the clypeus, depending upon the direction of the mouth-parts. 

 In the honey-bee and other Hymenoptera, the precoilae are similarly 

 situated as in the Mecoptera. The clypeo-labral suture is obsolete 

 in the Mecoptera studied. 



The labrum (1) of Panorpodes (Fig. 1) is of considerable size, seti- 

 ferous, narrower at tip, and each lateral margin is slightly emarginate. 



