8 



PROCEEDINGS OF THE NATIONAL MUSEUM 



western Atlantic region, may be found in Bigelow and Schroeder 

 (1948). 



Localities from which specimens were examined are represented on 

 the distribution maps by solid symbols; literatm-e records are repre- 

 sented by open symbols. 



In the tabidation of proportions values have been separated, as 

 much as practicable, by geographic area. In cases where paucity of 

 specimens does not permit an adequate comparison, and if the speci- 

 mens do not appear to be different from those from other areas, 



IOC 



POP 



Figure 3. — Diagram of hammerhead chondrocranium (terminology adapted from Daniel, 

 1922, p. 59): AF (anterior fontanelle), AMC (anterior mediorbital connection), ARC 

 (accessory rostral cartilage), IOC (innerorbital cartilage), OC (olfactory cartilage), OW 

 (olfactory wing), PMC (posterior mediorbital connection), POP (postorbital process), 

 PRC (preorbital cartilage), PRP (preorbital process), RC (rostral cartilages), RF (rostral 

 fenestra), RN (rostral node), RW (rostral wing). (Drawing by Paul Laessle). 



values have been combined. An exception to this was made in the 

 case of the single specimen of Sphyrna tudes from the Mediterranean. 

 This specimen is the holotype, and a comparison with material from 

 the western Atlantic was desirable. 



Classification 



The hammerhead sharks have, in the past, been accorded family 

 status by most of the investigators responsible for the major works on 



