44 Proceedings of the Biological Society of Washington. 



CeNTRARCHIDvE. 



29. Pomoxis annularis Rafinesqne. 



Adults abundant in the canal widewater above Rushville. Over 1600 

 were rescued and liberated in the Potomac River. The largest one 

 measured was 330 mm. long, but others which it is believed exceeded 

 this length were seen. In over 100 examples examined the number of 

 dorsal spines was 5 or 6, with two exceptions in which it was 7. McAtee 

 and Weed (Proc. Biol. Soc. Wash., Vol. XXVIII, 1915, p. 12) state that 

 this species and P. sparoides " are about equally common and occur both 

 in the river and canal." Among the large number seined at this point, 

 not a single example of the latter species was observed. 



30. Ambloplites rupestris (Rafinesque). 



Not uncommon in the canal. Examples from the point locally known 

 as Buzzards Hole were of a very light silvery color, some of them show- 

 ing scarcely any traces of black mottlings and with the size of the black 

 opercular blotch greatly reduced. When placed in alcohol, these assumed 

 the characteristic markings. 



31. Chaenobryttus gulosus (Cuvier & Valenciennes). 

 Abundant in the canal, more than 1,300 being rescued. Among those 

 taken was an individual which appears to be a hybrid with Lepomis 

 gibbosus. This has been described by the senior author (Copeia, No. 7, 

 New York, June 20, 1914). 



32. Lepomis cyanellus (Rafinesque). 

 Small examples abundant in the canal. This introduced species is 

 rapidly gaining a foothold throughout the region about Washington, 

 apparently preferring ponds, muddy, slow-moving streams, canals and 

 the like. 



33. Lepomis auritus (Linnaeus). 



Common in the canal and abundant in Little Seneca and Tenmile 

 creeks. 



34. Lepomis gibbosus (Linnaeus). 



Common in the canal. Over 3,000 of the three species of Lepomis were 

 rescued in this region. 



35. Micropterus dolomieu (Lacepfede). 

 Common in the canal below Violett's lock, but greatly outnumbered 

 above the lock by M. salmoides. According to local fishermen dolomieu 

 greatly outnumbers salmonoides in the Potomac along this stretch of the 

 canal, while farther up the river, below Harpers Ferry, the reverse is true. 

 The feeder from the Potomac enters the canal below the lock and the 

 small-mouthed bass may have entered in this manner, while above the 

 lock the fisli entered through a feeder from a point much higher up, 

 where the large-mouthed bass predominates. Now that both species are 

 being liberated in the Potomac in this region, this condition may be 

 changed. Two examples were taken in Tenmile creek. 



