442 Memoir Sears Foundation for Marine Research 



Range. Tropical to warm-temperate belts of the Atlantic; north regularly to Portu- 

 gal and occasionally to the English Channel, Welsh coast and Scotland, in the east; 

 Mediterranean; Azores; Madeira; TenerifFe; Canaries; Cape Verde Islands; Morocco; 

 Dakar; tropical West Africa and South Africa. In the west, north commonly to southern 

 New England and as a stray to Massachusetts Bay and Nova Scotia; south to Uruguay and 

 (nominally) to northern Argentina. It is also widespread in the tropical and warm-tem- 

 perate Pacific*' and probably in the Indian Ocean as well. But a more precise statement as 

 to the Indo-Pacific range of zygaena must await critical study of the Hammerheads as a 

 whole in that region. 



Occurrence in the Western Atlantic. It is not possible to present a satisfactory picture 

 of the distribution of S. zygaena in the western Atlantic from existing literature be- 

 cause of the recent discovery that many of the older accounts that ostensibly referred to 

 it may also have covered its companion species, d'l-plana (p. 419). In fact, the only western 

 Atlantic localities where the presence of zygaena (not including diplana or tudes) is posi- 

 tively established by pertinent information, either verbal or pictorial, as to shape of head, 

 teeth, relative proximity of the tip of second dorsal fin to caudal, or shape of skull, are: 

 Nahant in Massachusetts Bay; Cape Cod; southern Massachusetts in the general vicinity 

 of Woods Hole*" and the continental shelf in its offing; vicinity of New York; several 

 localities along the New Jersey coast; near Beaufort and Cape Lookout, North Carolina; 

 southern Florida on both coasts; the Virgin Islands; southern Brazil; Uruguay; and 

 (nominally) northern Argentina. But this is enough to prove it widespread all along the 

 American seaboard in low and midlatitudes. 



No doubt it is also responsible, at least in part, for the frequent reports of Hammer- 

 heads for the West Indian-Caribbean region, i.e., Porto Rico, Haiti, Jamaica, Cuba, Turks 

 Island, Trinidad, Dutch, French and British Guianas, Venezuela, the Atlantic coast of 

 Panama and likewise for Bermuda. Although definite information is lacking for the south- 

 ern part of the Gulf of Mexico, it is to be expected there generally, and no doubt it visits 

 the northern coast of the Gulf, at least in small numbers, for there are a few records of 

 Hammerheads for Louisiana. 



The most spectacular aspect of the occurrence of Hammerheads is their migration 

 northward (often in schools) in summer along the Atlantic seaboard, both inshore and out 

 along the continental shelf. Zygaena is chiefly responsible for this seasonal movement, the 

 most northerly records for diplana being from the offing of Delaware Bay (well offshore), 

 and for tudes from North Carolina (p. 434), whereas many zygaena have been posi- 

 tively identified from New Jersey to southern New England. For example. Hammerheads 

 of one sort or another are moderately common during the summer months near Charles- 



41. Specimens that we have examined from Peru, Panama, the Galapagos, Lower California and Japan do not differ 

 in any significant respect from the Atlantic specimens with which we have compared them in regard to teeth, pro- 

 portionate dimensions, shape of head, or fins. Hussakoff (Copeia, 34, 19 16: 63) had already reached the same 

 conclusion for Japanese specimens. 



42. A nine-foot specimen, taken in a fish trap in Buzzards Bay on August 6, 1934, and identified by a good photo- 

 graph published in the Boston Globe, is one of several well attested records for the region. 



