A. J. GtRovk 
487 
EXPLANATION OF PLATES XXVI—XXVIII. 
PLATE XXVI. 
Fig. 1. A transverse section through the head passing through the anterior supports of the 
transverse bar. (x75.) 
Fig. 2. A transverse section through the head showing the retractor muscles of the setae. ( x 234.) 
Fig. 3. A transverse section through the head showing the protractor musclesof thesetae. ( x 234.) 
Fig. 4. A transverse section through the head showing the commencement of the maxillary 
sclerites. (x234.) 
Fig. 5. A transverse section through the buccal cavity. ( x 140 ) 
Fig. 6. The musculature of the mandible. ( x 234.) 
Fig. 7. The musculature of the maxillary seta. ( x234.) 
PLATE XXVII. 
The figures in this plate are taken from a series of serial sections through the insect to show the 
arrangement of the sclerites in the buccal cavity, and the origin of the setal chamber and the 
labium. 
Fig. 1. A transverse section through the buccal cavity two sections posterior to the hypopharynx. 
( x217.) 
Fig. 2. Three sections further back from l. ( x217.) 
Fig. 3. The next section but one. The setal chamber is now beginning to appear. ( x 217.) 
Fig. 4. Six sections further back from 3. The epipharynx has now almost disappeared, and the 
setal chamber is very marked. ( x 217.) 
Fig. 5. The fourth section from the last. The commencement of the first joint of the labium has 
now appeared. (x2l7.) \ 
Fig. 6, The sixth section from 5. The setal chamber and the first joint of the labium are now 
quite clear. ( x217.) 
Fig. 7. Two sections further back from 6. The distal portion of the labium has now come into 
the section, and is nearing the proximal portion which is becoming separated from the body. 
( x 217.) 
Fig. 8. Three sections posterior to the last. The junction of the proximal and distal portions of 
the labium is now complete, and the organ is nearly separate from the body. ( x 217.) 
Fig. 9. The next section but one. The labium is now free, and projects downwards between the 
pro.coxae. (x217.) 
PLATE XXVIII. 
Fig. 1. A semi-diagrammatic figure of the head region to show the depression of the head and 
the position of the labium. The upper genal cone and procoxa are not shown in order that 
the front of the head and the labium, which would be otherwise hidden, may be seen. ( x 53.) 
Fig. 2. The details of the buccal region and the labium. ( x 106.) 
Fig. 3. The chitinous framework and tentorium seen from the posterior aspect. ( x 234.) 
Fig. 4. The details of the salivary pump. ( x 893.) 
Fig. 5. A side view of the salivary pump, showing the position of entry of the afferent salivary 
duct. (x420.) 
Fig. 6. A section through the salivary pump showing the attachment of the pump muscle. 
( x 420.) 
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