VI FIGURES 



Page 



21. Stygonectes barri, new species 88 



22. Stygonectes bifurcatus, new species 93 



23. Stygonectes russelH, new species 96 



24. Stygonectes russeUi, new species 98 



25. Stygonectes clantoni (Greaser) 103 



26. Stygonectes ozarkensis, new species 108 



27. Stygonectes bowmani, new species 112 



28. Stygonectes pecki, new species 118 



29. Stygonectes dejectus, new species 120 



30. Distribution of Stygonectes in North America 126 



31. Distribution of species of (S^y^onecies in the central Appalachians . . . 133 



32. Suggested phylogeny of emarginatus and flagellatus groups of Sty- 



gonectes 134 



33. Distribution of species of Stygonectes in central Texas 140 



34. Distribution of species of Stygonectes in eastern United States .... 145 



35. Distribution of tenuis group of Stygonectes in south-centi-al United 



States 151 



36. Suggested phylogeny of tenuis group of Stygonectes 152 



Tables 



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1. Representative North American genera of the Crangonyx section of 



Gammaridae 16 



2. Comparison of six representative North American genera of the Cran- 



gonyx section 19 



3. Appendage to body length ratios in females of Stygonectes gracilipes . . 39 



4. Comparison of mean size of sexually mature individuals from different 



populations of Stygonectes pizzinii (Shoemaker) 50 



5. Variation in the ratio of length of 1st antenna to length of body in 



different populations of Stygonectes russelli, new species 100 



6. Variation in the ratio of length of 1st antenna to length of body in two 



populations of Stygonectes clantoni 105 



