Lutroahus luteus LeConte, 1852. Larvae in calcareous encrustation or be- 

 neath submerged rocks; adults either at water line or on submerged 

 rocks or wood in travertine or other streams with high calcium con- 

 tent from central Texas and Oklahoma to eastern New Mexico, 



Genus Physemus LeConte, 1854 



Physemus minutus LeConte, 1854. Not known to be aquatic, but adults may 

 be found in damp places such as stream margins in southwestern 

 states from Texas to California. 



Subfamily Cephalobyrrhinae 



Genus Throsoinus LeConte, 1874 



Not known to be aquatic; adults are intertidal (two species along 



the Gulf shore of Texas and one species on the shores of southern 

 California) . 



Family PSEPHENIDAE (Lacordaire, 1854) 



Subfamily Eubriinae 



Genus Acneus Horn, 1880 

 (This genus merits study. Few larvae have been taken.) 



Acneus oregonensis Fender, 1951. Larvae on or under submerged rocks, 



adults along swift, rocky streams from Oregon to Olympic Peninsula 

 of Washington. 



Acneus quadrimaculatus Horn, 1880. Larvae on or under submerged rocks 



in rapid sections of streams, but in pools of quiet water protected 

 by boulders; adults on vegetation or rocks along swift, rocky 

 streams in California and Oregon, at elevations up to about 4,000 

 feet. 



Genus Dicranopselaphus Guerin-Meneville, 1861 



Dicvanoipselaphus vaviegatus Horn, 1880. The larva probably occurs on or 

 under submerged rocks or wood in streams; the adult near streams 

 from New York, Maryland, and Pennsylvania to Illinois. Rare. (No 

 one has reported the larva in the United States. It has probably 

 been mistaken for that of Ectopriaj or simply overlooked.) 



Genus Ectopria LeConte, 1853 



Ectopria nervosa (Melsheimer, 1844) . Larvae on submerged rocks and wood 

 in streams from Florida to Maine and Canada west to Iowa, Missouri, 

 and Oklahoma; adults on vegetation along streams or taken at lights. 



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