17. ORCA. 18. DELPHINAPTERUS. 187 



Pterygoid boues short and Jidpressed ; not in contact in the median 

 line. Temporal fossie long and rectangular. 



Measurements of the sTcull. — (Koy. Coll. Surg. London, JSTo. 2985. Old. 

 Tasmania.) Total length, 59.5"";* length of rostrum, 28.7'"'; breadth 

 of rostrum at base, 20.8""; at its middle, 18.8'"; breadth of iiiter- 

 masilhe at same point, 13.2'"; breadth between orbits, 33.3'"'; length 

 of temporal fossa, 19.1'"'. 



Habitat. — Pelagic. 



17. ORCA (^ray. 



Size very large. Rostrum broad and moderately elongated. Rostral 

 portion of interinaxillai narrow and Hat. Pterygoid bones separate. 

 Teeth few, 10 to 13; very large, with flattened roots. Vertebrte, 52. 



Head conical and depressed; beak wanting. Dorsal fin large and 

 prominent (remarkably so in the male). Pectoral fins large and very 

 broadly ovate. Color black, with a large and sharply contrasted ven- 

 tral area of white, forming a trident posteriorly, the lateral tines of 

 which extend up on the sides. 



ORCA GLADIATOR (Laccpc-de). 

 (Plate 45, figs, laud 2.) 



Cranial characters of the genus. 



Size very large. Head broad, conical, and depressed. Dorsal fin 

 erect, extraordinarily high in the male. Pectoral fins short and broad. 



Upper half of head, back, and fins black. Lower jaw, breast, and 

 belly whitish. The white area forms a trident posteriorly, the central 

 tine of which extends back to the vent, while the lateral tines extend 

 obliquely upward and backward on the sides. A large wkite blotch 

 behind the eye. A crescent-shaped area of purple extends across the 

 median line of the back behind the dorsal fin (? sometimes obsolete). 



Habitat. — Pelasric. 



Subfamily II. DELPHINAPTERIN^E. 

 18. DELPHINAPTERUS Lacepede. 



DELPHINAPTERUS LEUCAS (Pallas). 

 (Plate 40, figs. 1 aud 2.) 



Size moderate. Head globose, not prolonged into a snout. Neck 

 marked by a slight constriction. No dorsal fin, the center of the back 

 rising instead into a low, irregular ridge. Pectoral fins short, very 

 broad across the center, and obtusely pointed. 



Color white throughout. 



* A little sawn off the end of the rostrum. 



