CATFISH GENUS NOTURUS RAFINESQUE 49 



Pascagoula River 18 (10-11) 10.94; Biloxi Bay drainage 18 (9-11) 

 10.56; Bay St. Louis drainage 4 (10) 10.00; Tombigbee River 54 

 (9-12) 10.91; peninsular Florida 206 (8-12) 10.04; Escambia River 

 66 (10-11) 10.06; and total 976 (8-12) 10.19. 



Sqft dorsal rays: Most Michigan specimens and a sample from the 

 Ohio River, Indiana, have five rays more frequently than six; two 

 from New Hampshire and six of fourteen from Illinois have five rays; 

 otherwise the samples tend strongly toward six soft dorsal rays. The 

 following summarizes most of the data: Lake Huron drainage 111 

 (4-6) 5.32; Lake Erie drainage 47 (5-6) 5.40; Upper Peninsula, 

 Michigan 8 (5-6) 5.13; Lake Michigan drainage. Lower Peninsula, 

 Michigan 44 (4-7) 5.61; Michigan total 210 (4-7) 5.40; Indiana 31 

 (5-6) 5.48; New Jersey 16 (6) 6.00; North Carolina 4 (5-6) 5.75; 

 Missouri 30 (5-6) 5.87; Oklahoma 10 (5-6) 5.70; Texas 49 (5-7) 

 5.98; Louisiana 12 (6) 6.00; Biloxi Bay drainage 9 (6) 6.00; Tombigbee 

 River 20 (6-7) 6.05; peninsular Florida 102 (5-7) 5.97; Marianna, 

 Florida 6 (6) 6.00; and total 521 (4-7) 5.69. 



Vertebrae: No prominent variational trend in vertebrae is suggested; 

 however, the higher number in the central Gulf drainage specimens 

 seems to correspond with an increase in numbers of other parts. 

 Summaries by areas: Great Lakes basin 27 (33-36) 34.33; New Jersey 

 13 (35-36) 35.46; Nebraska 6 (32-34) 33.33; Indiana 31 (33-36) 

 34.19; Missouri 27 (33-35) 33.63; North Carolina 34 (34-36) 34.71; 

 Texas 26 (33-35) 34.15; lower Mississippi drainage 2 (33-34) 33.50; 

 Florida Parishes, Louisiana 2 (36-37) 36.50; Tombigbee River 5 

 (36-37) 36.60; Cahaba R., Alabama 2 (36-37) 36.50; peninsular 

 Florida 19 (32-35) 33.37; and total 194 (32-37) 34.30. 



The geographic variation in caudal, pelvic, and pectoral rays is 

 shown in tables 2 and 3. Gradients in these and in the general mor- 

 phology follow the geographic trend suggested by Hubbs (1940, p. 

 209). 



Summarizing the data, Atlantic coastal populations of gyrinus 

 appear to be much like those from the Mississippi Valley from approxi- 

 mately the same latitude, as there seems to be a gradient in most 

 characters from north to south in both areas. The number of soft 

 dorsal rays is reduced in the Great Lakes basin, but six, the normal 

 for Noturus is usually attained elsewhere. There are fewer pelvic, soft 

 pectoral, and caudal rays and fewer preoperculomandibular pores in 

 the north; aU of these increase in number southward, but the greatest 

 increase appears to be in the central Gulf drainage, notably the Mobile 

 Bay drainage, Alabama. This is unexplained. The Mobile drainage 

 population does not appear to be isolated. The increase, therefore, 

 may result from recent genetic fusion within the drainage of popula- 

 tions invading from the east and west. There seems to be no important 



