318 REPORT OF NATIONAL MUSEUM, 1884. 



(Gray). My reasons for so doing will be presented after the characters 

 of the exterior and skeleton have been described. 



EXTERNAL MORPHOLOGY. 



An adult male dolphin 85 inches in length. The general conforma- 

 tion of the body is similar to that of Delphinus delphis, but the dorsal 

 fin is higher and more arched, the pectoral fins are somewhat broader, 

 and the tail is deeper at the insertion of the flukes. The snout (the 

 upper and lower jaws taken together) is of moderate length, stout, and 

 about a third deeper than broad. The lower jaw does not project be- 

 yond the upper. The outlines of the lips are slightly concave. The 

 pectoral fins and the flukes present no peculiarity of form, being gently 

 and evenly convex anteriorly, and similarly concave posteriorly, and ob- 

 tusely pointed at the tip. The dorsal is strongly bent backward, a line 

 connecting the tip and center of the base, when prolonged making an 

 angle of 45° with a line connecting the extremity of the beak and the 

 notch of the flukes. The anterior margin is straight in the lower three- 

 fourths of its length, then rather strongly curved backward; the con- 

 cavity of the posterior margin forms an arc of a circle. 



The distribution of color is peculiar and somewhat difficult to describe. 

 Beginning at the base of the dorsal fin and passing downward the color 

 is first dark purplish slate, and becomes gradually lighter until the 

 middle of the side is reached. At this; latter point it grades somewhat 

 more rapidly into the pure white of the belly. From the line of the 

 anus backward, and from the region of the pectoral fin forward, the 

 dark color of the back extends down much lower. There is no pure 

 white posterior to the anus. The dark color involves the head and 

 beak and the extremity of lower jaw. It also borders the sides of the 

 latter to a depth of two or three inches. The entire body is covered 

 with spots of dark and light color, the largest of which are about 

 18 mm in length. A line connecting the center of the base of the dorsal 

 fin with the median line of the belly is twenty-two inches in length. 

 Beginning at the top, in the first four inches the body is about free from 

 spots; the next seven inches are occupied by large, light, slate-colored 

 spots on a dark ground ; and the remaining eleven inches are occupied 

 by large, dark, slate-colored spots on a light ground. Speaking gener- 

 ally, where the body is dark the spots are light, and vice versa. This 

 is true of the dark post-anal region and the head. The flukes, dorsal 

 fin, and pectoral fin are dark like the back, and all are covered with 

 small light-colored spots. The latter are scarcely perceptible on the 

 flukes. Upon examination of the plates, especially that showing the 

 under side of the body, it will appear that the dark spots, which are 

 roughly elliptical in outline, change direction in different regions of the 

 body. Beginning on the inferior surface of the lower jaw, it will be ob- 

 served that the axes of the spots converge toward the median line of 

 the belly as far as a point slightly anterior to the pectorals; then they 



