also true for the comparison involving the 

 Hudson and James populations (table 3). Unless 

 unusual samples were encountered, the Hudson 

 River collections were not drawn from the same 

 population as either the Delaware or James 

 specimens. 



The predorsal distance - standard 

 length relations of the collections within Chesa- 

 peake Bay were com pared for homogeneity. 

 The James samples were significantly different 

 in slope from the Rappahannock specimens 

 (table 4) and the former were similar in slope 

 but significantly different in intercept when 

 compared with samples taken in the York River 

 (table 5). The Potomac and James specimens 

 were also found to be similar in slope but sig- 

 nificantly different in intercept (table 6). The 

 Rappahannock samples were significantly differ- 

 ent in slope when compared with the Potomac 

 (table 8) and York (table 9) specimens. The re- 

 sults of the comparison involving the James and 

 Albemarle Sound samples indicate that both 

 collections could have been taken from the same 

 population (table 7) . 



The collections made above and below 

 Pinopolis Dam (the Santee -Cooper River System) 

 proved to be homogeneous in the regression of 

 predorsal distance on standard length (table 10). 

 Therefore, the two populations, if they do exist, 

 cannot be separated on the basis of predorsal 

 distance. An "F" value significant at the 1 -per- 

 cent level resulted when the downstream 

 samples were compared with the Albemarle 

 Sound collections for homogeneity of regression 

 coefficients (table 11). 



The regression of predorsal distance on 

 standard length was homogeneous in two com- 

 parisons: the James samples with those from 

 Albemarle Sound, and the Santee -Cooper up- 

 stream and downstream collections . All other 

 comparisons between two locations resulted in 

 the hypothesis that the samples were not drawn 

 from the same population . 



Head length - -The assumption of homo- 

 geneity of the nine regression coefficients, for 

 the regression of head length on standard length, 

 was posed as the null hypothesis and tested by 

 the appropriate "F" test in an analysis of co- 

 variance (table 1). The "F" value found was 



significant at the 1 -percent level. The alterna- 

 tive hypothesis that of the regression coefficients 

 not being homogeneous is therefore accepted. 



The Hudson River samples possessed a 

 head length - standard length relation that was 

 significantly different from the relation found 

 in both the Delaware and the James specimens 

 (tables 1 and 2). The character head length 

 shows that the Hudson River samples were not 

 taken from the same population as the Delaware 

 or James collections. 



The regression of head length on standard 

 length was compeared among samples taken from 

 the Chesapeake Bay area. The slope of the James 

 River specimens was significantly different from 

 that of the Rappahannock and York collections 

 (tables 4 and 5) . The regression coefficients of 

 the James and Potomac samples were homogene- 

 ous but the regression differed significantly in 

 intercept (table 6). When the James River col- 

 lections were compiared to samples taken from 

 the nearest area studied outside the bay, Albe- 

 marle Sound, nonsignificance of both slope and 

 intercept resulted (table 7) . The Rappahannock 

 River samples were found similar in slope but 

 different in intercept when compared with the 

 Potomac collections (table 8). The Rappahannock 

 and York specimens differed significantly in 

 slope (table 9). The samples secured in Chesa- 

 peake Bay do not appear to have been taken from 

 a homogeneous population. Using the regression 

 of head length on standard length as an index, the 

 various river systems of Chesapeake Bay appear 

 to have their own distinct populations . 



The regression of head length on standard 

 length was not statistically different between the 

 Santee -Cooper upstream and downstream samples 

 (table 10), or between the downstream samples 

 and the Albemarle Sound collections (table 1 1) . 

 Therefore, head length indicates that both the 

 upstream Santee-Cooper and the Albemarle 

 Sound samples could have been taken from the 

 same population as the downstream Santee-Cooper 

 collections . 



The regression of head length on standard 

 length was significantly different for all compar- 

 isons made between samples taken from the 

 James River northward. Comparisons made be- 

 tween samples taken from the James River and 



