REVISION OF CARCHARHINID SHARK GENERA — SPRINGER 615 



Distribution. — ^Eastern Pacific Ocean from Peru to southern 

 California, from waters as deep as 15 fathoms. 



Relationships. — Within the subgenus Rhizoprionodon, R. longurio 

 forms a separate offshoot from the remaining three species, differing 

 mainly in its high tooth counts, long snout, and upper labial furrow 

 lengths. 



Material. — Mexico: Baja California: San Juanico Bay, USNM 

 196122 (1: 388 mm.), USNM 190594 (2: 402-403), UCLA W52-246 

 (12: 385-466), SIO H51-306 (2: 351-358); Concepcion Bay, USNM 

 46852 (1: 916); beach one-half mile south of San Felipe, USNM 

 190590(1: 385);Sonora: Salinas Bay, SU 17329 (2: 398-460) ; Mazat- 

 lan, USNM 28306 (1: 517, syntype of Carcharias longurio), USNM 

 28330 (1: 792, syntype of Carcharias longurio), USNM 29551 (1:518, 

 syntype of Carcharias longurio), SU 11594 (1: ca. 685). panama: 

 NMV [no number] (1 : 525) ; 1-3 miles southeast of Isla Taboga, 2-4 

 miles off Rio Pacora, UCLA W53-273 (4: 301-349); Panama City, 

 USNM 78101 (1: 583); Panama City, fish market, USNM 79291 

 (1 : 702). PERU: Gulf of Guayaquil: 81°13' W. and 4°13' S., USNM 

 127756 (2: 657-688); off Mt. Organos, Cabo Blanco, USNM 127776 

 (5: 282-300, embryos from 1540 mm. female}. 



Rhizoprionodon (Protozygaena) lalandei Valenciennes 



Figures 10, 11; Plate 2b 

 Carcharias (ScoUodon) lalandii Valenciennes in Miiller and Henle, 1841, Sys- 



tematische Bescbreibung der Plagiostomen, p. 30 (Rio de Janeiro, Martinique, 



Guadeloupe). 

 ScoUodon intermedins Garman, 1913, Mem. Mus. Comp. Zool., vol. 36 (text), 



p. 115 (Philippines, East Indies). 



Diagnosis. — Upper labial furrow well developed, 1.4-2.1 percent 

 of t.l. ; precaudal centra slightly elongate in posterior monospondylous 

 region (plate 2 b); precaudal vertebrae greater in number than caudal 

 vertebrae; anterior margin of pectoral fin shorter than total length 

 of first dorsal fin (equal to, in 1 out of 33 specimens) ; snout in front 

 of nostrils 4.4-5.1 percent of t.l. in specimens less than 575 mm. 

 t.L, 4.4-4.7 percent of t.l. in specimens over 575 mm. t.l.; total teeth 

 in outer row of upper jaw 25; total teeth in outer row of lower jaw 

 24 (23 in 2 out of 21 specimens); total enlarged hyomandibular pores 

 on both sides of head usually more than 16 (25 out of 26 specimens); 

 first dorsal origin usually over level of appressed pectoral inner corner, 

 ranging to just behind inner corner; origin of second dorsal fin usually 

 over anal axil but may occur as far forward as above posterior fourth 

 of anal base; tip of appressed pectoral fin reaches to below level of 

 anterior third or less of first dorsal base. Males matming at about 

 500 mm. 



Description (see table 15). — Precaudal vertebrae 79-90 (only 

 4 specimens out of 45 with less than 85); caudal vertebrae 67-79; 



