Fig. 1. Crangonyx vitreus (Cope). — 2 , 5.2 mm long, enlarged 20 diameters.

Fig. 2. One of the first pair of legs seen from the outside, enlarged 48 diameters.

Fig. 3. One of the second pair of legs, x 48.

Fig. 4. End of the abdomen, side view, X48. — a, telson ; 6, posterior caudal stylet ; c, second caudal stylet ; d, first

caudal stylet. Fig. 5. Crangonyx packardii Smith (details all magnified 48 diameters; 5 to 8, 2, 5.5 mm long; 9 to 11, J, about 7.5 mm

long). — Lateral view of the head. Fig. 6. End of one of the first pair of legs, outside. Fig. 7. The same of the second pair. Fig. 8. End of the abdomen, lateral view. Fig. 9. One of the first pair of legs, outside. Fig. 10. One of the second pair of legs, outside. Fig. 11. Autennula and antenna, side view.

Fig. 12. Crangonyx antennatus Pack. — Terminal joints of the antennule, showing the olfactory rods. Fig. 13. The entire- antennule. 13a, basal joint with four auditory setae ; 136, fourth joint of the same with its ramus. Fig. 14. Antenna, with four auditory seta?. Fig. 15. Crangonyx mucronatua Forbes, Illinois. — Antenna, end enlarged; 15a, the same more highly magnified ; 156>

fourth joint still more magnified. (The setulae of the auditory setar are fewer than in Cascidotaa.) Fig. 16. Crangonyx vitreus Cope (?) .—Basal joint of antennule. (Compare with Fig. 13a.)