22 PROCEEDINGS OF THE ACADEMY OP 



ORCA Gray. 



The species of this genus are the wolves of the ocean, and occur in all. seas, 

 swimming in small companies, and living by violence and plunder. 



Two species of the genus are described briefly by Capt. Scammon, which 

 differ from each other much as the two Atlantic species do, in respect to the 

 form of the dorsal fin. In one in each case the fin is exceedingly high and 

 erect, in the other broader, more oblique and less elevated. 



OrCA RECTIPINNA Cope. 



The dorsal fin extremely elevated — " six feet or more in the larger males," 

 whose length "averages 25 feet" at right angles to the axis of the body, and 

 one-third the length from the end of the muzzle. Muzzle slightly acuminate. 

 Color black, more or less white below (" most in females") with white lines on 

 the sides from the eye sometimes to the hinder margin of the dorsal fin. ? No 

 large white spot behind eye. This species appears to be distributed from Cali- 

 fornia southwards. 



Orca ater Cope. 



The dorsal fin much shorter, wider, and more obliquely direltted. Black, 

 with a large white spot behind the eye. Muzzle ? not acuminal'e. ? A brown 

 dorsal crescent behind fin. 



The North West coasts from Oregon to the Aleutian Islands. 



The species of this genus from the Atlantic Ocean, whose colors are known, 

 reverse the arrangement existing in the Pacific species. According to Lillje- 

 borg, the 0. gladiator has the straight elevated fin, and the large white 

 spot on the side, while the 0. e s c h r i c h t i i, which has the less elevated and 

 oblique fin, does not present this peculiar mark. In both these animals the 

 belly is white, as is also the case with 0. eschrichtii. In 0. a t e r the 

 inferior surfaces appear to be entirely black, or nearly so. 



It will no doubt be found to be the case with both these Orcas that their fe- 

 males will have less elevated dorsal fins than the males. This is known to be 

 the case with the Atlantic species, as described by Eschricht and Reinhardt. 



DELPHINUS. 



Many species of true dolphins have been described as inhabiting the Pacific 

 Ocean, by French and American travellers. Those enumerated by Capt. Scam- 

 mon are not sufficiently described to be identified. They are probably the fol- 

 lowing : 



Delphinus obliquidens Gill. 



Lagenoihynchis obliquidens Gill, Proc. Acad. Nat. Sci. Phila. 1865, \%1. The 

 Bottle Nose Grampus, Scammon. 



? Delphinus styx Gray. 



Zoology, Erebus and Terror, Tab. Cope, Proc. Acad. Nat. Sci. Phila, 186G, 201. 

 Common Porpoise, Scammon. ^ 



The cranium described by me as above accompanied one of the Phocaena 

 V o m e r i n a Gill, and was, like it, covered with a dark varnish, which is not 

 the case with any other specimen in the Museum of the Academy. Whether 

 it really came from the California coast or not is entirely uncertain. It is 

 equally uncertain whether it is the species mentioned by Capt. Scammon, iu 

 case this should prove to be the fact. It is a species of the size and propor- 

 tions of the typical dolphins or porpoises. 



DELPHINAPTERUS Less. 

 Delphinapterus borealis Peale. 

 Cassin's Mammalogy, U. S. Expl. Ex. 30, Tab. vii, 2. 



This species was taken in the North Pacific, nearer the coast of Oregon than 

 any other laud. It may possibly be the Right Whale Porpoise of Scammon. 



[April, 



