ENEMIES OF APHIDES. 407 



EXPLANATION OF PLATES XVIII. & XIX. 



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Plate XVIII. 



Details of Aphidivorous Hemerohiince. 



Fig. 1. — Maxillary palpus of Larva of Hemerohius, showing the pecu- 

 liar chitinous incomplete rings. 



2. — Mandible of same larva, exhibiting the toothed termination 

 and the fine serrations of the edge. 



3.— Maxilla of same. The opening at the extremity through 

 which the juices of the aphis victims are ingested is clear, 

 and also the fold extending longitudinally down the organ. 



4. — Labial palpus of same larva, showing in the widened termi- 

 nal joint the same arrangement of incomplete rings of chitin. 



These organs are much smaller than the similar organs of 

 Chrysopa perla, shown in PI. XII., but are magnified in a 

 much greater degree. 



5. — Threads of silk-like substance, spun by the same larva to 

 form its cocoon. These threads were spun on a cover-glass, 

 and the glutinous nature of the secretion is clearly visible at 

 the points of attachment. No indication of duplication or 

 structure of any kind is visible. 



,, da. — Portion of same, more highly magnified. 



,, 6. — Extremity of abdomen of ^ Hemerobius inconspicuous. 



,,7. — ., >} ^ H. nitudulus. 



,,8. — ,, „ ^ H. Micans. 



,,9. — ,, ,, 6 H. hitmuli. 



,,10. — ,, ,, 6 H. marginatus. 



,,11. — ,, ,, 6 H. liynhatus. 



„ 12. — ,, ,, c? H. subnehulosis. 



,,13. — ,, ,, 6 S. Nervosus. 



,,14. — ,, ,, ? -ff • Concinnus. 



,,15. — ,, ,, S H. Concinnus. 



The last 10 figures are after those given as characteristic 

 by Mr. R. McLachlan in his Memoirs on the Neuroptera. 



Plate XIX. 



Fig. 1. — The wing venation of Chrysopa perla, after Bowerbank, in 

 the Entomological Magazine, showing the circulation through- 

 out the nervures. The arrows show the direction taken by 

 the fluids within. 



,, 2. — A branching vein, showing the manner in which the included 

 trachea divides. 



