May, 1916] IIo7nopterous Studies. Part II 305 



mark the region where labrum and clypeus meet. The shape of 

 the labrum is broadly rectangular, with the anterior margin 

 generally rounded off, and forming a covering for the basal 

 joint of the labium. Projecting from under its anterior margin 

 and fitting into the groove at the base of the labium is the small, 

 peglike epipharynx (epi.). On an external view the epipharynx 

 appears as part of the labrum, but on close examination it will be 

 seen to run back as the dorsal wall of the pharynx. 



The Occiput or the posterior part of the dorsal surface of 

 the head can not be differentiated from the vertex. However, 

 by viewing the head in its caudal aspect it may be seen as the 

 large sclerite surrounding the occipital forearm. Attached to 

 the ventral surface of the occiput, is the gula or gular region, 

 which is very small in the Jassoid head, owing to the deflection. 

 The gula consists of a small membrane attached at one end 

 to the base of the occiput and at the other to the basal joint 

 of the labium. 



The Genas proper cannot be distinguished from the maxillary 

 plates — an amalgamation of the two sclerites taking place 

 early in the development of the insect's head. No trace of a 

 suture is to be found and we can only refer to the gen^ in 

 general terms as that region surrounding the compound eyes 

 on either side of the face and attached to the maxillary plates, 

 for the greater part. 



Ocelli. — The ocelli (o) where present are two in number. 

 As stated before, in the Tettigoniellidae (Fig. 5), they are 

 located on the mid-dorsal surface of the vertex, while in the 

 Bythoscopidse they are situated on the face (Fig. 3). The 

 position in the case of the last named family is probably owing 

 to development of the epicranium, which occupies the greater 

 part of the dorsal region of the face. However, in the Jassidae 

 and TyphlocybidcC (where present), the ocelli are located on 

 the cephalo-lateral margins of the head. On examining the 

 internal structure of the head, it will be found that branches 

 of the dorsal arms of the tentorium proceed to the head just 

 beneath the ocelli. This was found to be the case in practically 

 all the forms examined. The ocelli are small, clear, circular 

 or oval structures, which are generally raised above the general 

 level of the head. Frequently they are colorless or glassy, 

 but in some cases they are pigmented with red or black. 



