NO. 3539 HAMMERHEAD SHARKS — GILBERT 5 



Wayne J. Baldwin, University of California at Los Angeles; the late 

 Miss Margaret H. Storey, Stanford University; Dr. David K. Caldwell, 

 Los Angeles County Museum; Mr. William I. FoUett and Mrs. 

 Lillian Dempster, California Academy of Sciences; Dr. Earl S, 

 Herald and Mr. Robert Dempster, Steinhart Aquarium, San Fran- 

 cisco, Calif.; Drs. Arthur D. Welander and Kelshaw Bonham, Uni- 

 versity of Washington; Dr. John C. Briggs, University of South 

 Florida; Drs. Reeve M, Bailey and Robert Rush Miller, University of 

 Michigan; Mr. Frank Williams, Director, Guinean Trawling Survey, 

 Lagos, Nigeria; Prof. Enrico Tortonese, Museo Civicio de Storia 

 Natm-ale, Genoa, Italy; Prof. M. Benazzi and Mr. Alberto Lanfranchi, 

 University of Pisa Museum, Pisa, Italy; Dr. Wolfgang Klausewitz, 

 Senckenberg Museum, Frankfurt-on-Main, West Germany; and to 

 the authorities of the British Museum of Natural History. Finally, 

 I woidd like to express my special appreciation to Mr. Paul Laessle, 

 staff artist of the Department of Zoology, University of Florida; 

 Mrs. Dorothea B. Schultz; and Mr. Craig Phillips, who are responsible 

 for the illustrations and graphs. 



Materials and Methods 



Specimens examined or recorded are from the following museum 

 collections: Academy of Natiu-al Sciences of Philadelphia (ANSP) ; 

 British Museiun (Natural History) (BMNH) ; California Academy 

 of Sciences (CAS); Field Museum of Natural History (formerly 

 Chicago Natiual History Museum) (FMNH); Museum of Com- 

 parative Zoology, Harvard University (MCZ) ; Museum National 

 d'Histou-e Naturelle (Paris) (MNHN) ; Scripps Institution of Oceanog- 

 raphy (SIO); Stanford University (SU); University of California, 

 Los Angeles (UCLA); Florida State Museum, University of Florida 

 (UF); University of Miami, Institute of Marine Science (UMML); 

 University of Pisa (Italy) (UP); University of Michigan, Museum 

 of Zoology (UMMZ); United States National Museum (USNM). 



Proportional measm-ements for aU specimens were made according 

 to the methods described by Springer (1964, pp. 562-568). Measure- 

 ments are expressed in thousandths of total length (TL). Various 

 external morphological characters are illustrated and labelled in 

 figures 1 and 2. While the specimen on w^hich figure 1 is based is 

 not a member of the family Sphyrnidae, most of the characters apply 

 equally to the hammerhead sharks. 



Head-pore and chondrocranial terminologies (figs. 2, 3) are adapted 

 from Daniel (1922, p. 59) and Tortonese (1950a, p. 9), respectively. 



All radiographs of the chondrocrania were made on type M Kodak 

 Industrial film with a "hard ray" machine (Miller, 1957, pp. 29-40). 



