4.36 Memoir Sears Foundation for Marine Research 



Platysqualus tudes Howell-Rivero, Proc. Boston Soc. nat. Hist., 41 (4), I 936: 44 (ident. probable because of 

 large size, I 2 to 14 ft., Cuba). 



Doubtful References: 



Zy gaena tudes Cuvier, Regne Anim., ill. ed., 1843: pi. 1 17, fig. I ; Osorio, J. Sci. math. phys. nat. Lisboa, (2) 

 J, 1894: 182 (name only, C. Verde Is.); J. Sci. math. phys. nat. Lisboa, (2) 5, 1898: 200 (name only, 

 C. Verde Is.) ; Metzelaar, Trop. Atlant. Visschen, 191 9: 189 (by ref. to Rochebrune and Osorio as above, 

 trop. W. Afr.). 



Sphynia tudes Miillcr and Troschel, in Schomburgic, Reisen Brit. Guiana, 1840—44, 5, I 848: 642 (one re- 

 ported as seen, Demerara) ; Machado, Feces Cadiz, 1 857: 9 (Spanish coast, name only) ; Berg, Ann. Mus. 

 nac. B. Aires, (2) i (4), 1895: 8 (Montevideo, Muldonado, no evidence for ident.); Fowler, Proc. 

 Acad. nat. Sci. Philad., 60, igo8: 66 (meas., 8-in. spec, not diagnostic, and ident. doubtful because of 

 small size, Surinam) ; Ribeiro, Rev. Mus. paul., 1918: 107 (name only, Santos, Brazil) ; Devincenzi, An. 

 Mus. Hist. nat. Montevideo, (2) / (4), 1920: 119 (name only, Uruguay) ; An. Mus. Hist. nat. Monte- 

 video, (2) (6), 1925: 323 (name only); Marelli, Elcnc. Sist. Fauna B. Aires (1922—23), 1924: 546 

 (name only, Uruguay, Argentina); Pozzi and Bordale, An. Soc. cient. argent., /20, 1935: 151 (name 

 only, north. Argentina). 



Cestracion tudes Meek and Hildebrand, Field Mus. Publ. ZooL, 15 (l), 1923: 59 (descr. appears to be pardy 

 tiburo). 



Not S-pkyr?ia tudes Ribeiro, Arch. Mus. nac. Rio de J., 14, 1907: 157, pi. 5 (photo of head appears to be 

 dif.ana, see p. 420, Maria Farinha, Pernambuco, Brazil) ; Arch. Mus. nac. Rio de J., Fauna brasil. Peixes, 

 2(1) Fasc. I, 1923: 14 (same record as foregoing). 



Sf hyrna zy gaena (Linnaeus), 1758 



Common Hammerhead 



Figures 85, 86 



Study Material. Eleven specimens of both sexes, from 510 to about 1,780 mm. long, 

 from: Muldonado, Uruguay; Rio de Janeiro, Brazil; New York; off Nahant in Massa- 

 chusetts Bay; Cape Cod; and off Woods Hole, Massachusetts (Harv. Mus. Comp. ZooL). 

 Others from Virginia Beach, Virginia, and Buzzards Bay, Massachusetts (U.S. Nat. 

 Mus.). Specimens from Woods Hole, Massachusetts (U.S. Bur. Fish.). Several others 

 caught in the offing over the continental shelf by members of the Woods Hole Oceano- 

 graphic Institution and identified by us, and ten small specimens from Peru, Panama, the 

 Galapagos, Lower California and Japan (Harv. Mus. Comp. ZooL, No. 382, 383, 421, 

 441, 515, 1042, and U.S. Nat. Mus., No. 51289, 51291, 71774, 77711). 



Distinctive Characters. The very differently shaped head is enough to separate 

 zygaena at a glance from tiburo (cf. Fig. 86 A with 82 B). It is easily distinguished from 

 diplana, bigelowi and tudes by the evenly convex anterior outline of the head in the mid- 

 line (not indented) ; further from diplana by the additional differences summarized under 

 that species (p. 415); further from bigelowi and tudes by the much more slenderly acu- 

 minate tip of its second dorsal fin, and further from tudes by its much more erect first 

 dorsal fin. 



Description. Proportional dimensions in per cent of total length. Male, 524 mm., 



