348 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 52. 



Scale Formula 19—21—19—17. 



This formula may be regarded as the normal for this immediate 

 region. It is found in 56 per cent of the specimens; of these, 39 per 

 cent are males. 



Male. 



Female. 



The influence of sex on this character is evident. On the average 

 the VI row tends to be longer in that it begins further forv/ard and 

 extends more to the rear. The IV row also ends further back. This 

 lengthening of the scale rows is associated with the stouter body in 

 the female. 



It will be noted that No. 52170 is bilaterally symmetrical. It is 

 comparatively rare for the scale rows to arise and to be suppressed at 

 exactly the same gastrostege levels. 



