288 MEMOIRS OF THE CARNEGIE MUSEUM. 



Ecologically this species is found imder a number of conditions, but there is 

 no doubt that it prefers rather quiet water and sandy-muddy bottoms. Strong 

 currents and rough bottoms do not suit it, and although occasionally found in 

 riffles, it probably has in such cases been washed out of the quieter pools. In the 

 quiet water below riffles, where there is more or less muddy bottom, or in slowly 

 running water with fine gravel, sand, and mud, it is abundant. This accounts 

 for its absence in mountain-streams, and its absence or scarcity in the large rivers, 

 while its most favorable localities are in the plateau-streams, or the streams within 

 the glacial drift, which are more sluggish and have finer bottom material. For 

 this reason, this species is also much inclined to go into lakes. 



General distribution: Type locality, According to Lamarck this species comes 

 from the Susquehanna and Mohawk Rivers. Its presence in the Susquehanna 

 has never been confirmed, but in the Mohawk it has been found subsequently 

 (Lewis, 1860; Marshall, 1895), and also at other places in the Mohawk and Hudson 

 drainages, as well as in the Erie Canal (DeKay, 1843; Simpson, 1891; Marshall). 

 The Mohawk should be designated as the type-locality. This is in the Atlantic- 

 drainage, but the chief distribution of this species is in the Interior basin. 



In New York it is also known from the St. Lawrence-drainage (Marshall, 

 1895), and material in the Carnegie Museum from the Genesee system shows that 

 it is the typical luteola, which is found there. It is also found in New York in 

 the Ohio-drainage, in Ischua Creek, Cattaraugus Co., and Lake Chautauqua 

 (Marshall) . How far the typical form extends northward in this region is unknown. 

 It has been reported from Canada (Ontario, and also westward in the St. Lawrence- 

 drainage up to Lake Superior, and from the Hudson Bay-dramage) but in these 

 northern parts it seems, that its place is largely, if not entirely, taken by certain 

 varieties, chiefly rosacea (See below). Yet the tj^pical form is certainly present 

 north of Lake Erie as is shown by specimens in the Carnegie Museum (Conestogo 

 River) (also reported from northern Michigan, in Manistique River, Schoolcraft 

 Co., by Winslow, 1917). 



Westwards L. luteola is found practically aU over western Pennsylvania, 

 Ohio, Indiana, and Illinois, crossing over into the lake-drainage at various points, 

 and it extends northward through Iowa, Wisconsin, and Minnesota into the 

 drainage of the Red River of the North, although, as has been said, it seems in 

 the northern parts of its range to give way to varieties. 



Lewis (1877) calls attention to the fact that this species has not been recorded 

 from "any stream much south of the latitude of the Ohio River," but that possibly 

 it is present in Kentucky. Material in the Carnegie Museum shows that it occurs 



