670 



PROCEEDINGS OF THE NATIONAL MUSEUM 



TOTAL LENGTH IN MM 



Figure 4. — hums, short-finned only, showing change with growth of the relative propor- 

 tions of the first dorsal fin (identified specimens are types of nominal species). 



head length; the head length relative to the distance between the 

 pectoral fin axil and the pelvic fin origin; and the distance between 

 the origins of the pectoral fin and first dorsal fin relative to parts of 

 the head length. Figures 3-5 and table 1 do not support Bigelow 

 and Schroeder's criteria for distinguishing Atlantic and Pacific species 

 of Isurus, nor Smith's recognition of two or more species within each 

 of the major oceans. Instead the figures and table provide fairly 

 strong evidence that short-finned makos undergo considerable change 

 with growth in some proportions and are variable in others. The 

 amount of variation is large, but much of it may be due to differences 



^ 3.8 F 



3.6 



3.4 



y 3.2 



2.6 



Sr 2.4 



2.2- 



1500 2000 2500 



TOTAL LENGTH IN MM 



3000 



Figure 5. — Isurus, short-finned only, showing growth change in the height of the first dorsal 

 fin relative to prepectoral length (identified specimens are types of nominal species). 



