4 PROCEEDINGS OF THE NATIONAL IVIUSEUM vol. 119 



Another problem encountered was the scarcity of large specimens; 

 however, I know of no taxonomically significant characters, with the 

 exception of the pelvic claspers, that are not evident in the embryos 

 and young. Although it would be desirable to know the full extent 

 of the various morphometric changes occiu-ring during growth, such 

 data probably woidd not alter the present taxonomic conclusions. 



The degree of confidence in the taxonomic conclusions reached in 

 this paper is dependent largely upon the number of specimens available 

 and on the extent of geographic coverage. The decision reached 

 concerning the status of Sphyrna mokarran, therefore, does not rest 

 on as firm a basis as for S. lewini and S. zygaena because far fewer 

 specimens of mokarran were seen and the geographic coverage of the 

 last two species was much better. Only one specimen of Sphyrna 

 tudes from the Mediterranean was examined, and, as stated previously, 

 S. couardi was represented only by a head. In the case of S. tudes, 

 however, only one other specimen of this species outside of the western 

 Atlantic area is Imown by me to be present in collections. 



Acknowledgments 



This study was supported by contracts between the Smithsonian 

 Institution, Ofiice of Naval Research (ONR no. 1354(09)), and the 

 Atomic Energy Commission, and was carried out while the author 

 was a research associate of the U.S. National Museum. The aid 

 and cooperation of the following people have been invaluable during 

 the coiu-se of this work: Dr. Leonard P. Schidtz, U.S. National Mu- 

 seum, who supervised the project; Drs. J. A. F. Garrick, Victor G. 

 Springer, Ernest A, Lachner, WiUiam Ralph Taylor, Stanley H. 

 Weitzman, and Mr. Robert H. Kanazawa, U.S. National Museum; 

 Dr. Shelton P. Applegate, Los Angeles County Museum, for most 

 of the information on dental variation in Sphyrna lewini and for other 

 information on shark classification; Madame M. L. Bauchot, Museum 

 National d'Histoire Naturelle, Paris, France, for loan of the type 

 specimens of Zygaena tudes; Dr. Bruce B. Collette, U.S. Fish and 

 Wildlife Service, Washington, D.C., for informing me of a specimen 

 of Sphyrna couardi he had collected; Dr. Daniel M. Cohen, U.S. 

 Fish and Wildlife Service, Washington, D.C.; Mr. Stewart Springer, 

 U.S. Fish and Wddlife Service, Stanford, Calif. ; Drs. Giles W. Mead 

 and Henry B. Bigelow, Mr. WilKam C. Schroeder, and Mrs. Myvanwy 

 Dick, Museum of Comparative Zoology, Harvard University; Mr. 

 Loren P. Woods, the late Mrs. Marion Grey, and Miss Pearl Sonoda, 

 Field Museum of Natural History, Chicago, lU.; Dr. James E. Bohlke, 

 Academy of Natm-al Sciences of Philadelphia; Drs. Carl L. Hubbs, 

 Robert Wisner, and Richard H. Rosenblatt, Scripps Institution of 

 Oceanography, University of California; Dr. Boyd W. Walker and Mr. 



