A. J. Grove 
4H5 
made out in cross sections, and the two parts can be separated with com¬ 
parative ease, and as this frequently happens during the process of section 
cutting, they are consequently often so seen in the sections. In addition to 
these interlocking grooves and ridges, two grooves are found traversing the 
whole length of each seta, with the result that, when the two setae are placed 
together, two channels are formed. These channels are unequal in size, and 
in the region of the buccal cavity the larger one is anterior to the smaller. 
Similar channels have been described by many authors as being present in 
other Hemiptera, and the larger channel is usually termed the suction canal, 
grv. labi. sal. can. 
Text-fig. 1. The upper figure is a section through the buccal cavity to show the interlocking 
arrangement of the maxillary sclerites and the grooves, in which the setae lie, formed between 
the maxillary sclerites and the epipharynx. ( x 363.) 
The lower figure is a transverse section through the groove of the labium showing the 
setae in situ, and the interlocking of the maxillary stylets with the formation of the suction- 
canal and the efferent salivary canal. ( x 1466.) 
(For explanation of lettering see p. 488.) 
and the smaller one the efferent salivary canal. In the region where the 
maxillary setae are closely associated with each other, the resulting piercing 
organ is roughly rectangular in section (text-fig. 1), the long sides curving 
slightly inwards and the short sides outwards. The two component parts of 
the organ are, however, roughly triangular in outline, such as would result 
from the drawing of a diagonal across the rectangle. The middle portion of the 
section is occupied by the two canals, the suction canal being considerably 
larger than the efferent salivary canal. The interlocking ridges and grooves 
which hold the component parts together lie closely beside these canals along 
the line of the diagonal. The fine tubular continuation of the cavity within 
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