28 BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



The report of the Mission (p. 290) stated that many "hammer-head 

 sharks" were seen, some as far south as Ilo and as far offshore as 

 50 miles. One was caught 20 miles northwest of Chmca North 

 Island, and a "number" were taken on trawl lines near Cabo Blanco. 

 The catch at Cabo Blanco includes the fish from which the head was 

 removed, and six others, listed as varying in length from 1.05 to 

 1.38 cm. A length of 510 to 600 cm. is said to be attained. 



According to the report of the A-Iission (p. 291) there may be more 

 than one species, which may possibly be indicated by the several local 

 names given at the head of this account. It is quite possible, of course, 

 that S. tudes, which is widely distributed in tropical seas, though no 

 definite American Pacific coast records south of the Gulf of California 

 seem to exist, occurs along the coast of Peru. It is also entirely 

 possible that one or all three species, S. vespertina, S. media, and 

 S. corona, recently described by Springer (1940, pp. 161 to 169, figs. 1 

 to 7) may occur there. S. vespertina was reported from Panama City 

 and Guayaquil, Ecuador; S. media from Mazatldn, Mexico, and 

 Panama; and S. corona from Panama. A key to the species known 

 from the tropical Pacific on the American side is offered above as an 

 aid in recognizing additional species if taken in Peru. 



According to the report of the Mission (p. 290) hammerhead sharks 

 are "consumed fresh, dried or salted." 



Range. — Tropical and temperate seas; recorded from the American 

 side of the tropical Pacific from Mexico, Panama, Peru, and the 

 Galdpagos Islands. 



Family GALEORHINIDAE: Gray Sharks 



Body elongate ; tail more or less compressed ; head depressed ; snout 

 depressed, rounded to more or less pointed; eyes lateral, with nicti- 

 tating membranes; mouth inferior, weU arched; nostrils below snout; 

 spiracles small or wanting; two spineless dorsal fins, the first entirely 

 before ventrals, the second more or less opposite anal; caudal directed 

 more or less upward ; no keel. 



A large family of sharks that has been divided into smaller families 

 by some authors, but the regrouping does not seem satisfactory to 

 the present writer. 



KEY TO THE GENERA 



a. Teeth in pavement, with more than one series functioning, with small cusps in 

 some species; spiracles small; labial folds well developed. _ Mustelus (p. 29) 

 aa. Teeth compressed, more or less triangular, a single series functioning; spiracles 

 present or absent. 

 b. Spiracles absent. 



c. Labial folds wanting or rudimentary. 



d. First dorsal placed posteriorly, the midpoint of its base being nearer 

 insertion of ventrals than pectorals; teeth all with serrate margins. 



Prionace (p. 36) 



