PLATE VIIa. 
Fig. 1. Average dorsal bristle of Lagisca magellanica, . . . x 90. 
Fig. 2. Ventral bristle of the same (from the middle of the series), . x 90. 
Fig. 3. Tip of average dorsal bristle of Eulagisca corrientis, . . x 90. 
Fig. 4. Bristle from the middle of the ventral tuft of the same form, . x 90. 
Fig. 5. Average dorsal bristle of Lagisca tenuisetis, . . . x 400. 
Fig 6. Tip of one of the large forms from the same tuft, . . . x 400. 
Figs. 7, 8. Superior ventral bristles of the same species, . . . x 40o 
Fig. 9. Bristle with shorter tip, from the middle of the ventral series of 
the same, ....... x 400. 
Fig. 10. Tip of a dorsal bristle of Lagisca per acuta, . . . x 350. 
Fig. 11. Extremity of one of the middle bristles of the ventral series of the 
same species, . . . . . . x 350. 
Fig. 12. Tip of a dorsal bristle of Polyeunoa Icevis, . . . . x 210. 
Fig. 13. Ventral bristle of the foregoing, . . . . . x 210. 
Fig. 14. Tip of a dorsal bristle of Lagisca magellanica, var. grubei, . x 210. 
Fig. 15. One of the superior ventral bristles of the same form, . . x 90. 
Fig. 16. Tip of a bristle from the middle of the ventral series of the fore- 
going, ...... X 210. 
