1922] Otanes: Head and Mouth-Parts of Mecoptera 313 



setiferous and is fused with the labrum (1) in ah the species studied. 

 Its ventral extent, however, is marked by the position of the precoilse 

 (pr). In Merope and Boreus, the fronto-clypeus has completely merged 

 with the vertex owing to the obsolescence of the entire epicranial 

 suture; in Bittacus, the fronto-clypeus is wholly separated from the 

 vertex by the epicranial arms, and in Apterobittacus, the fronto-clypeus 

 is fused with the vertex along its dorsal margin owing to the obsolescence 

 of the transverse portion of the epicranial arms, whereas in Panorpodes 

 it is fused with the vertex along its lateral margins, brought about by 

 the disappearance of the lateral parts of the epicranial arms. 



There is a pair of membranous areas dorsad of the fronto-clypeus 

 which connect the antennas and the head (Fig. 1). These are the 

 antacorias (an) and are located on the vertex in the Mecoptera. The 

 size of the antacoriee in the Mecoptera varies considerably, being smallest 

 in Bittacus and most pronounced in Panorpodes. Surrounding each 

 antacoria is a narrow, ring-like sclerite known as the antennaria (ar). 

 There is a cuticular projection into the antacoria from the ventro- 

 lateral portion of the antennaria, which is somewhat prominent in 

 Panorpa (Fig. 31) and Boreus (Figs. 14, 32), designated as the antacoila 

 (aa). Yuasa (1920) referred to the antacoila as being the "chitinized 

 pin" in the cockroach, as described by Miall and Denny. 



The compound eyes (ce), regarded as the appendages of the first, 

 ocular or protocerebral segment are of considerable size in the Mecoptera 

 and are especially prominent in Bittacus (Figs. 3, 28) in proportion to- 

 the size of the head. Viewed from the lateral aspect, the compound 

 eyes are oval except in Merope (Figs. 7, 30), where they are oblong 

 and emarginate on the cephalic margin, giving them a distinctly 

 reniform shape, thus resembling the eyes of some Hymenoptera, as 

 Vespa maculata. In Bittacus the eyes are slightly emarginate on the 

 caudal margin, the reverse of Merope, giving the eyes also a kidney- 

 shaped appearance. Each compound eye is surrounded by a narrow 

 ring-like area, which is prolonged entad as an annular strongly chitinized 

 plate. This area is called the oculata (ol) and was designated by 

 Comstock and Kochi (1902) as an "ocular sclerite." These authors 

 considered the oculata as the proximal segment of an ocular appendage. 

 Crampton (1921), however, is not inclined to consider the oculata as a 

 sclerite, stating that this area is not marked off by a true suture and 

 objects to the consideration of the oculata by Comstock and Kochi 

 as being the basal segment of an ocular appendage. Yuasa (1920) 

 observed the oculata as being always present in all the species of 

 Orthoptera which he studied and as well developed in the species 

 having large compound eyes, as Mantis religiosa and Melanoplus 

 dijferentialis. Peterson (191G) likewise recognized the oculata in 

 Diptera and calls it the ocular sclerite, using the term proposed by 

 Comstock and Kochi. 



The normal number of ocelli is present in all of the genera studied, 

 with the exception of Merope. They are more or less circular in outline 

 and are most prominent in Bittacus and in Apterobittacus. They are 

 located on the vertex as is true in all Entoptera. In Bittacus (Figs. 



