Contents 



Page 



Introduction 1 



Objectives 2 



Historical review 3 



Procedure 6 



Terminology 9 



Taxonomy 12 



Acknowledgments 14 



Systematics 15 



Family Gammaridae 15 



Crangonyx section 16 



Genus Stygonecies 17 



Evolution 124 



Distribution and origin 124 



Speciation and dispersal 132 



Conclusions 168 



Summary 170 



Literature cited 172 



Figures 



Page 



1. Preserved specimen of Stygonectes reddelli Holsinger from Whit ef ace 



Cave, San Saba Co., Texas facing page 16 



2. Stygonectes emarginatus (Hubricht) 24 



3. Stygonectes viundus, new species 27 



-i. Stygonectes morrisoni, new species 29 



5. Stygonectes cooperi, new species 32 



G. Stygonectes stellmacki, new species 34 



7. Stygonectes gracilipes, new species 37 



8. Stygonectes conradi, new species 41 



9. Stygonectes spinatiis, new species 44 



10. Stygonectes pizzinii (Shoemaker) 48 



11. Stygonectes indentatiis, new species 54 



12. Stygonectes tenuis tenxtis (Smith) 59 



13. Stygonectes tenuis potomactis, new subspecies 63 



14. Relation of antennal length to standard length (body length excluding 



appendages) in Stygonectes tenuis potomacus, new subspecies, from 



seeps in Burleith Woods, Washington, D.C 64 



15. Stygonectes allegheniensis, new species 67 



16. Relation of antennal length to standard length (body length excluding 



appendages) in Stygonectes allegheniensis, new species, from seeps, 

 springs, and wells in Herkimer and Onondaga Counties, 



New York 70 



17. Stygonectes hayi (Huliricht and Mackin) 72 



18. Stygonectes alabamensis alabamensis (Stout) 76 



19. Stygonectes montanus, new species 83 



20. Stygonectes elatus, new species 85 



V 



