78 Psyche lApril 



the head now much resembles that of an adult, but for the further 

 lengthening out which reduces the large epicranial lump behind 

 the eyes. The post-embryological development is very similar 

 to that of Sycanus croceovittatus. 



Up to the time of hatching the tips of the setse project only 

 a little beyond the apex of the epipharynx, and are free, but as 

 soon as the young has freed itself from the amnion the tips of 

 the setse are placed into the trough, and pushed beyond the tips, 

 of the labium. It is able to do this for two reasons; one, because 

 during development the basal part of the seta, with its tendons 

 and muscles, has grown back into the head and formed a loop 

 which reached even onto the prothorax (Fig. 15 m. t. s.). This 

 is straightened out at birth, and pushes the seta-tip through the 

 trough of the labium. The second reason is because of a length- 

 ening of the anterior part of the seta after casting the amnion. 



These studies lead us to the following conclusions. 



What is termed the frons by many writers we consider as 

 clypeus, and their clypeus as lab rum. The clypeal region is 

 often very indistinct, and amalgamated with the head-capsule. 

 The lorse (mandibular sclerites of Meek) have no connection 

 with the mandibles, but are lateral developments of the clypeal 

 region. The dorsal and outer pair of setse are the mandibles, 

 developed direct from the first pair of appendages behind the 

 stomodseum of the embryo, and articulated in the normal position, 

 viz.: — on the oral margin between the clypeus and maxillse. 

 The ventral and inner pair of setae are part of the maxillse, devel- 

 oped directly from the distal joint of the second pair of appendages 

 behind the stomodseum of the embryo, the basal joint being 

 directly developed into the maxillary plate (maxillary sclerite 

 of Meek, Maxillarhocker of Heymons). The complete amalga- 

 mation of this portion of the maxilla with the head-capsule, 

 leaving no line or suture of juncture, is unique among insects, and 

 constitutes one of the most difficult points for interpretation. 

 In many Heteroptera the maxillary plate fuses with the lateral 

 edges of the basal labial segment. The labium is formed by the 

 entire fusion of the 2nd maxillse. In many of the Heteroptera 

 the basal joint fuses with the head-capsule and the ventral 

 edges of the maxillary plates. The salivary syringe (salivary 

 injector of Meek, Wanzenspritze of German writers) is homologous 



