240 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 37 



canal-like structures are formed — one by the apposition of the 

 pointed tips of the hypopharynx and epipharynx and the other by 

 the elongated and tapering end of the common salivary duct. These 

 points have not been carefully studied by the previous workers. It 

 completely excludes the possibility of the mixing of the saliva and 

 the sap sucked by these insects. 



Maxillae (figs. 2 and 3). — The maxillae of Homoptera and also 

 of Heteroptera consist of a maxillary plate and a stylet. The latter is 

 joined with the plate by a weak, thin lever. The maxillary stylets are 

 provided with double grooves on their inner faces, which form the 

 suction and ejection canals of the bugs. At the base of each stylet 

 there is a maxillary gland in Pyrilla as well as in Idiocerus. The 

 maxillary gland is now widely known in Homoptera. There are two 

 sets of muscles which bring about the movement of the maxillary 

 stylets in Pyrilla, viz ( i ) protractors, which arise from the maxillary 

 plate and are inserted at the base of the stylet, and (2) retractors, 

 which arise from the dorsal wall of the head capsule, and are also 

 inserted at the base of the stylet. In Idiocerus there are four muscles 

 in relation with each maxilla. The first of them forms the retractors 

 of the stylets which arise from the dorsal wall of the head capsule 

 and are inserted at the base of the stylet. The muscles of the second 

 set also arise from the head capsule and are inserted on the lever. 

 They also help in the retraction of the stylet. The third muscle arises 

 from the ventral extension of the gena and is attached to the base of 

 the maxillary stylet. The fourth muscle arises in close proximity to 

 the third and is attached to the lever. The third and fourth muscles 

 are the protractors of the stylet. 



Mandibles (figs. 3, 4, and 5). — The mandibles of Homoptera con- 

 sist of a mandibular plate and a stylet. The stylet is connected to the 

 plate with the lever. In Idiocerus these plates are demarcated from 

 the genal region and are evidently not derived from the hypopharynx 

 as stated in the case of Cicada by Snodgrass and Butt. The mandibu- 

 lar bristle is bilobed at the base. One of the arms is produced as an 

 apodeme to which the retractor muscles are attached. The other is 

 articulated with the lever which in its turn articulates with the base 

 of the mandibular plate. The mandibles of Idiocerus are provided 

 with three muscles. One of them is the protractor of the mandible 

 and arises in close proximity to the maxillary muscle from the man- 

 dibular plate. The second and third muscles are the retractors of 

 the mandibles. One of them is inserted on the lever and the other is 

 inserted on the base of the stylet. In Pyrilla the mandibles are moved 



