AQUATIC MIDGES AND SOME RELATED INSECTS. 5 1 



The food itself consists almost exclusively of diatoms, and as the number of kinds 

 of diatoms in such streams is few and as those found on exposed ledges where the larvae 

 feed are even less varied the variety is not great. Figure 57 shows a typical selection 

 of the food from the stomach of one of these larvae. The many unique features in the 

 habits of this insect seem to limit its life and activities to a very restricted environment 

 to which it seems but poorly adapted, if the infrequent capture of adults and the evident 

 scarcity of pupae can be taken as criterions. From the above observations it might 

 readily be considered as a species which had only recently acquired the aquatic habit. 



EXPLANATION OF FIGURES. 



ChIRONOMCS BRASENI.E. 



Fig. i. — Ventral aspect of the epipharynx; a, lateral arm; co, epipharyngeal comb; e. chitinous 

 claws; h, horseshoe-shaped chitinized area; p, lateral process, s, pectinate hairs; t, thickened border 

 of the labrum; x, chitinous process. 



Fig. 2. — Lateral view of the strongly chitinized structures somewhat diagrammatic; p, lateral process; 

 s, setae and pectinate hairs; u, clypeus; (other structures as above). 



Fig. 3. — Lateral aspect of the mandible (md); j, pectinate setae; q, external process; m, portion of 

 the adductor muscle and its thickened exteria; v, extensor muscle. 



Fig. 4. — Median aspect of the left side of the head; c, cardo (position indicated); g, galea; i, in- 

 ternal chitinous process; j, pectinate setae; 1, lacinia; la, labium; m, adductor muscle; md, mandible; 

 p, maxillary palpus; st, stipes; u, clypeus; v, extensor muscle; w, center of articulation of the galea 

 and lacinae. 



Fig. 5. — Ventral aspect of a portion of an epicranial plate; i, internal chitinous process; r, antenna; 

 u, clypeus. 



Fig. 6. — Dorsal aspect of mandible; j, pectinate setae; o, articular surface of mandible; q, external 

 process. » 



Fig. 7. — Dorsal aspect of hypopharynx; b, posterior lobe; e, backward pointing setae; k, arm or 

 chitinous process; th, chitinous plate; z, exit of the salivary ducts. 



Fig. 8. — Dorso-ventral aspect of the hypopharynx; d, salivary duct; f, chitinous ring; k, arm or 

 chitinous process; th, chitinous plate. 



Fig. 9. — Antenna, lateral aspect; 1, Lauterborn 's organ ; n, sensory spine. 



Fig. 10. — Ventral view of the head; c, cordo; d, salivary duct; c, epicranial plate; la, labium; 

 md. mandible; mx, maxilla; r, antenna; u, clypeus. 



Fig. 11. — Lateral aspect of the maxilla; c, cardo or striated membrane; g, galea; 1, lacinia; p. 

 palpus; pf, palpifer; st, stipes; w, center of articulation of the galea and lacinia. 



Fig. 12. —Lateral aspect of a portion of the epicranial plate; c, cardo or striated membrane, la, 

 labium; pr, chitinous process limiting the movement of the mandibles; st, stipes. 



Fig. 13. — Ventral aspect of the anterior margin of the labium. 



Fig. 14. — Labium of young larva. 



Fig. 15. — Posterior segments of the larva; b, branchial gills; ca, caudal filaments; c, claws. 



Fig. 16. — Lateral fin on the 8th segment of the pupa; ca, chitinized area. 



Fig. 17. — Hypopygium of the imago, dorsal aspect. 



Fig. iS.— Wing. 



Fig. 19. — Portion of an egg mass. 



Fig. 20. — Tracings of the larval burrows in the leaves of Brasenia. 



Fig. 21. — The same as fig. 20. 



Fig. 22. — The same as fig. 20. 



Fig. 23. — Diagrammatic drawing of the larval burrow greatly enlarged; a, silk supporting threads; 

 b, section of the epidermis cut out by the larva; c, canopy composed of larval castings; d, epidermal 

 slab used as the sides of the larval burrow; e, edge of epidermis and the underlying parenchyma; f , vein 

 of the leaf; g, mucus gland. 



Fig. 24. — Pupal chamber on the leaf of Casta Ha odorata;c, idioblast; p, anterior portion of pupa molt. 



Fig. 25. — Cross section of a Castalia odorala leaf showing its general structure; a, stomata; b, upper 

 epidermis; c, idioblast; d, lower epidermis; e, air space. 



