THE LIFE-HISTORY OF FRESII-WATER MITES. 369 



m. Dorsal view of larva just hatched. 

 n. Ventral view, somewhat larger. 

 o. Agrion pulckelhim, Lind., showing parasites on under-side of 



thorax. 

 p. Another species of dragon-fly, showing parasites on posterior 



segments. 

 q. Dorsal surface of one of the larvae of Arrhmwrus ghbator. 

 r. Ventral surface of ditto. 



Plate 27. 



a. Ranatr a linearis, Linn., showing parasitic larvae of Hydrcwhna 



globosa. 



b. One of the larvae detached, showing dorsal plate peculiar to 



all larvae of this genus. 



c. Corixa geojfroyi. 



d. Another Corixa. Specific name unknown, showing parasitic 



larvae under wing-case. 



e. Leg of Corixa geqffroyi, showing parasites. 



Plate 28. 



■a. Xotonecta glauca. 



b. Hind leg of same, showing parasites attached. 



c. The parasitic larvae when first attached. 



d. Ditto, showing growth of soft-skinned portion of body. 



e. Ventral surface of same. 



f. The same full-grown, showing traces of nymph inside. 



g. The envelope as left on the host after the nymph has broken 



away. 

 h. Dytiscus marginalis, showing parasites on ventral surface and 



leg. 

 i. Dorsal surface of Xcpa cinerea. 

 j. Ventral surface of ditto. 

 k. Larval parasite detached. 



Plate 29. 



a. Caenia obscura, Mg. This figure was drawn by W. Wesche. 



b. Abdomen, showing position of parasitic larvae of Hydryphantes. 



c. Figure of the larva. 



