THE DOLPHINS. 95 



SECTION" lY.-THE BAY PORPOISE. 



PnooaiNA YOMEEiNA, GUI. (Plate xviii, fig. 2, 3, 4.) 



This peculiar species of Dolphin is the least in size of the entire whale tribe 

 inhabiting the Pacific Rorth American Coast. When fully matured it may attain 

 the length of six feet, but those we have had opportunity to measiu-e fell con- 

 siderably short of these dimensions. Usually the adults are not more than four 

 and one -half feet between linear extremes. The body of the male is jet black 

 above, a little lighter below ; and while the female is of the same color above, it 

 is lighter on the sides, with a narrow black streak running from the corner of the 

 mouth to the pectorals, and the lower portion of the animal is of a milky white- 

 ness, yet the pectoral and caudal fins are black underneath, or of a dark gray. 

 Occasionally, however, both males and females are found with the larger portion, 

 or the whole, of their dorsal and caudal fins white. The former are of triangular 

 shape, and placed very nearly midway between the animal's extremities. The 

 caudal fin varies much in its contour, sometimes being quite broad and straight 

 on its posterior edge, which is slightly notched in the centre ; in other specimens 

 the caudal lobes are lunate, and united present a forked appearance. Its pectorals 

 are extremely small and placed low. Its head is somewhat pointed, but destitute 

 of the slender, elongated beak of the Ddjphmua Bairdli, and the Right Whale 

 Porpoise. The anterior portion of the animal resembles that of both the Orca and 

 the White - headed Grampus-. Its eyes are placed about two inches behind the 

 corner of the mouth, and nearly in a line with it. Its ears are two inches 

 from the eyes, and these minute orifices would not be noticed by the casual 

 observer, as they are less than a sixteenth of an inch in diameter. The spiracles 

 are placed a little forward of the eyes, and unite in one where they pass through 

 the fleshy part of the cranium. The valve which covers them is convex on its 

 posterior side. When the animal respires this valve is turned downward. Both 

 upper and lower jaws are furnished with teeth, which in the adults are thin, flat, 

 and broadest near their summits. In one example, a female four feet long, taken 

 at San Francisco, California, the number was ff, and in another, |^. In a male, 

 four feet eight inches in length, taken in Port Townsend Bay, Washington. Terri- 

 tory, the number was the same as last mentioned. 



The following measurements and memoranda were carefully taken from a male 

 specimen obtained at Port Townsend, Washington Territory, April 28th, 1869 : 



