6 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 119 



Additional proportional measurements, other than those found in 

 the tables, were also taken. These have not been included, however, 

 since they give no information not already expressed by the measure- 

 ments in the tables. 



DISTANCE BETWEEN NOSTRILS 



NOSTRILS OR NARES 



VENTRAL SIDE OF HEAD 



NEARLy SYMMETRICAL CAUDAL FIN 



Figure 1. — External features of a shark with indications for measurement: a, lateral view 

 of body; b, ventral view of head and comparison of caudal fins. (Drawings by Craig 

 Phillips, from Garrick and Schultz, 1963, pp. 5, 6.) 



As indicated in plates 7c, d, one of the main chondrocranial features 

 separating Sphyrna corona and S. media is rostral cartilage length. 

 This difference has been expressed as a ratio by dividing the rostral 

 cartilage length by the distance betw^een the tips of the preorbital 

 cartilages (fig. 17). Values were obtained by measuring the distances 



