62 



INTERNAL STRUCTURE OF HEAD AND PROBOSCIS 



gustatory papillae (figs. 3, 30, g.p.) have already been described. 

 The aperture at the end of the papilla leads into a fine duct, which 

 ends in a pyriform sensory bulb (s.g.p.). The tracheae (tr.) can 

 be seen running through the cells, some of which contain several 

 nuclei, and from their appearance are probably derived from the 

 fat-body. No tracheal sacs could be found either in the oral lobes 



^s--f-- 



FiG. 30. Portion of a transverse section of the oral lobes, showing the two types of 

 gustatoij sense organ, etc. 



<7..s>. Gustatory seta. g.}}. Gustatory papilla. hy. Hypodermis under which 



lies a pigmented layer. p.s. Pseudo-trachea in section. s.g.p. Sensory 



bulb of gustatoiy papilla. .s.^j. Sensoij bulb of gustatoiy seta. tr. Trachea. 



or at their bases, but the annular tracheae are continuous with 

 those of the proboscis. The haemocoel of the oral lobes is well 

 developed. This supports the view set forth by Kraepelin, and 

 with which I agi-ee, that the inflation of the oral lobes is due to the 

 blood. I consider that the extension of the proboscis is due to the 

 inflation of the tracheal sacs of the head. The proboscis having 



