4 Proceedings of the Biological Society of Washington. 



LIST OF FISHES. 

 Beloiv falls A hove falls 



Hypentelium nigricans Hybognathus nuchalis 



Seraotilus atromaculatus Semotilus atromaculatus 



Pimephales notatus Leuciscus vandoisulus 



Notropis amoenus Rhinichthys atronasus 



analostanus 



cornutus 



hudsonius 

 Ericymba buccata 

 Campostoma anomalum 

 Lepomis gibbosus 

 Boleosoma olmstedi 



Discussion of Virginia Creeks. 



Difficult Run is excluded because we know so little of its 

 fauna. It is distinguished from all of the other creeks by pos- 

 session of the brook trout. 



Abrupt descent near the mouth is a striking characteristic of 

 the other Virginia creeks and it is the chief factor in determining 

 the nature of their fish fauna. Scotts Run, with an initial single 

 obstacle 25 feet in elevation and a steep series of rapids immedi- 

 ately adding 75 feet more, nevertheless has the largest number 

 of species occurring above the falls. The writers feel sure this 

 is due to other factors than feasible water connections or climb- 

 ing abilities of the fish. An old mill now stands about a mile 

 from the mouth of the creek, and it is possible that small fishes 

 collected elsewhere for bait may have been released above the 

 dam or in the race supplying the mill. Other agencies of 

 transportation and other motives are conceivable. 



The more normal conditions are represented by Dead and 

 Turkey Runs. Dead Run falls 120 feet in its last half mile in 

 a series of rapids which includes one particularly long steep 

 waterslide with never more than a thin sheet of water running 

 over it. Only those redoubtable climbers, the fall fish (Semotilus 

 atromaculatus) and the black-nosed dace (Rhinichthys atronasus) 

 have surmounted these obstacles. Repeated investigations of 

 the upper reaches of the brook have revealed no other species. 



Turkey Run, although falling 100 feet in its last half mile 

 has no single fall of any magnitude. Its plunge into the river 

 is by means of a large number of small rapids. This probably 

 explains why two more species (Hybognathus nuchalis and 



