May, 1916] Homopterous Studies. Part II 303 



of the palpifer or the combined lacinia and galea. (6) The 

 maxillary-plate represents the cardo and stipes." In their 

 discussion of the Homology of the Hemipterous mouthparts, 

 no reference is made to the Jassoidea, except that the Tetti- 

 goniellids can be easily homologised with the Cicada. Beyond 

 this reference to the Jassoid head the writer has been unable 

 to find further treatment of the subject. 



In the following discussion of the Jassoid head, the fixed 

 parts will be considered first and then the free or movable 

 parts. 



Fixed Parts of the Head. (PL XX, Figs. 1, 2, 3, 4, 5). 



The Jassoidea agree with the other Hemipterous families 

 in the general arrangement of the head and mouthparts. The 

 head is greatly deflexed and the mouthparts are attached to the 

 caudo-ventral portion of the capsule, with the result that the 

 beak or so-called proboscis is directed caudally between the 

 first pair of thoracic legs. 



Head-Capsule. — As in a generalised insect, the head of the 

 Jassid is composed of a number of sclerites, which have become 

 united to form the head-capsule, and this becomes the external 

 skeleton of the head. To this capsule, the various appendages 

 of the head are attached and articulated. In the head it will 

 be found that no trace of the primitive sclerites forming the 

 head-capsule is to be found, for they have either disappeared 

 or amalgamated with other sclerites. The various regions on 

 the Jassoid head were indicated before, and only those areas 

 which can be definitely recognized as sclerites will be considered 

 here. 



The dorsal region (v) of the head (i. e., the vertex) is not 

 separable from the front or frons (Fr), and there is no trace of a 

 suture between them, as one would expect. Together with 

 the genffi and occiput, the vertex and front constitute the 

 epicranium. 



The vertex (v) varies considerably in size from a mere narrow 

 region in the Bythoscopidse to a greatly elongated area in the 

 Tettigoniellids (especially in the Tribe Dorydini). It usually 

 bears the paired ocelli (o) ; thus in the Family Tettigoniellidag 

 they are located on the disk or surface, in the Jassidse on the 

 cephalo-lateral margin near the eyes, and in the Typhlocybidae 

 (when present) also on the cephalo-lateral margin. But in 



