5. PRODELPHINUS P. C.ERULEO-ALBUS AND EUPIIROSYNE. 163 



Head with a distinct elongated beak. Dorsal and pectoral fins fal- 

 cate (?tbe former triangular in P. fnvnatus). Color black or gray 

 abov^e, light below, with spots or longitudinal bands. 



PRODELPHINUS C^RULEO-ALBUS (Meycu). 

 (Plate 14, figs. 1 aiul2.) 



Head rounded and much arched. Snout very flat, longer than in D. 

 delpliis and less compressed; lower jaw protruding a little beyond the 

 upper jaw. Pectoral and dorsal fins pointed and not deeply emargi- 

 nate behind. 



Teeth |J, conical, pointed, and curved inward. Vertebne: 0. 1 ; 

 D. 14; L. and Ca. 52+. Skull similar to that of P. euphrosyne, but 

 with small temporal fosste, which are directed upward. 



Back and forehead dark steel blue. A very dark blue stripe starts 

 from the dorsal fin, and, passing forward, ends abruptly in front. A 

 narrow blue stripe on the sides from the eye to the vent, expanded at 

 the posterior end. Pectoral fin blue-gray, connected by a colored band 

 with the ring which surrounds the eye. Belly, snout, and other parts 

 of the body white. (IMeyen.) 



Habitat. — Coast of South America, near the mouth of the Eio de la 

 Plata. 



PRODELPHINUS EUPHROSYNE (GrayJ. 

 (Plato 15, figs, land 2.) 



Body robust; snout long; dorsal fin high and falcate; pectoral fins 

 small. 



Upper parts black; sides blackish; margins of the jaws blackish, 

 their extremity entirely black; throat and belly white; circumference 

 of the eye black. A narrow black baud (broadest at the extremities) 

 from the eye to the vent, with a branch given oft" above the base of the 

 pectoral fins and running a short distance downwards and backward. 

 A band of white, broadest in the middle, separates the lateral black 

 band from the dark color of the sides above; another and broader 

 black band extends from the eye to the base of the pectoral fin and has 

 along its center a white area which communicates with the white of the 

 throat immediately below the eye. Fins black, with a narrow line of 

 white on their anterior margin (sometimes absent). 



Teeth JJ- Vertebra: C. 7; D. 15; L. 22; Ca. 32 = 76. 



Measurements of the exterior. — Total length (on the curv^es), 209.7""; 

 tip of beak to the anterior base of the dorsal fin, 93.2""; breadth of 

 flukes, 42<^™; length of anterior margin of pectoral fin, 30.5"". (Pucheran : 

 B. marginatus.) 



Measurements of the siviill. — {ilfus. cVEist.nat. Type of Z>, margina- 



