Heterl-tmnius koehelei (Martin, 1927) . In rapid mountain streams from 

 northern California to British Columbia. 



Genus Hexaoylloepus Hinton, 1940 



Hexaoylloepus ferrugineus (Horn, 1870). On travertine, under rocks, in 

 gravel, and sometimes on wood, chiefly in riffles of streams with a 

 calcium content from Mexico through central Texas into the 

 Arbuckle Mountain region of south central Oklahoma and into south- 

 eastern New Mexico. 



Genus Maaronyohus Muller, 1806 



Macronyohus glahvatus Say, 1825. On submerged wood and debris in 



streams of the eastern and central states from Florida to Maine and 

 eastern Texas and Oklahoma to Wisconsin. Sensitive to sewage and 

 many industrial wastes, such as those from plating, textile, and 

 viscose rayon plants. 



Genus Micvooylloepus Hinton, 1935 

 (Other species will soon be described, including one from springs 

 in Death Valley, California.) 



M-iovocylloepus browni (Hatch, 1938) . Warm spring in Montana. 



Miaroaylloepus moccpus La Rivers, 1949. Warm springs in southeastern 

 Nevada. 



Micvooylloepus moccpus fraxinus La Rivers, 1949. Warm springs in 

 southeastern Nevada. 



Micvooylloepus pusillus (LeConte, 1852) . Versatile and common on sub- 

 merged wood and debris, under rocks, or in gravel of streams from 

 Mexico east to Florida, west to California, and north to Oregon, 

 Idaho, Wyoming, South Dakota, Missouri, Tennessee, and among the 

 eastern states to Maine. Tolerant of siltation and turbidity, but 

 sensitive to sewage and such industrial wastes as those from rayon 

 plants and plating mills. 



Micvooylloepus pusillus ccptus (Musgrave, 1933) . Northern Florida to 

 Virginia. 



Micvooylloepus pusillus pusillus (LeConte, 1852) . Virginia to New 

 York. 



Micvooylloepus pusillus lodingi (Musgrave, 1933) . Southeastern (Gulf) 

 coastal plain. 



Micvooylloepus pusillus pevditus (Musgrave, 1933) . Peninsular Florida. 



Micvooylloepus pusillus similis (Horn, 1870). West of the Rocky Mountains, 



Micvooylloepus thermavum (Darlington, 1928) . Warm springs in north- 

 western Nevada. 



Genus Navpus Casey, 1893 

 (A new species will soon be described.) 



Navpus angustus Casey, 1893. In gravelly or rocky rapids of clear 

 streams in the coastal range of California. 



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