7. LAGENOEHYNCHUS — L. ACUTUS. 169 



LAGENORHYNCHUS ACUTUS Gray. 

 (Plato 23, figs. 1 amis.) 



Form stoat; greatest j^irtli of tlie body anterior to the middle of its 

 length. Forehead gradually sloping; beak very short, a mere rim; a 

 depression between it and the forehead on either side of the head ; dor- 

 sal fin high and recurved, and attenuated in the distal half. Pectoral 

 fins broad at the base, pointed. Flukes large; caudal ridges very 

 strongly developed. 



Upper jaw, forehead, back, and fins black; sides of head and body 

 gray. On the upper part of the sides of the tail the gray color ])asses 

 into dusky yellowish; lower down on the sides, below the dorsal fin, an 

 oblong area of white. A narrow black baud extends along the sides 

 from the base of the flukes to about the line of the dorsal fin ("? some- 

 times absent); another line of black extends from the base of the pec- 

 toral fins to a point between the eye and the corner of the mouth ; the 

 eye is surrounded by a circle of black, from which a line extends for- 

 ward to the beak; the vent is in a small black area. The base of the 

 rtukes interiorly and the adjacent margin of the tail are whitish. The 

 margin of the lower jaw is sometimes black. 



Teeth 5;. Vertebnr,: C. 7, D. 15, L. 10, Ca. 39=80. Skull broad 

 and massive; rostrum broad, its length one-half the total length of the 

 skull. Proximal expanded portiou of the maxilhc broad (breadth 

 across post-orbital processes of frontal equal to length of rostrum). 

 Premaxilhe flat, their outer margin sinuate. Temporal fossae elongate 

 and extending obliquely upw.ird. Pterygoid bones in contact; large, 

 with lateral keels and obtuse crests, the posterointernal free edge 

 transverse and not strongly emarginate; vomer appearing in the 

 center of the palate as a ridge about 5"" long; it is joined by a linear 

 slip of the intermaxilhe, which extends tlieuce along the distal half of 

 the palate to the extremity of the rostrum, becoming broader distally. 



Memnrements of the exterior {from DuguUJ). — Total length (along 

 the back), 99 inches (251.5' '") ; extremity of snout to pectoral fin, IG 

 inches (40.G"") ; to dorsal- fin, 37 inches (93.9'"'); vertical depth of 

 dorsal fin, 13 inches (33'^'"); length of pectoral fins, 13 inches (33'"'); 

 breadth of flukes, 25 inches (03.5'"'). 



Measurements of the sJcull. — (U. S. National Museum, 14244, Cape 

 Cod). Total length, 42.5 '" ; length of rostrum, 21.G "" ; breadth of ros- 

 trum at base, 11.4""; at its middle, 7.0"' ; breadth between orbits, 

 21.G""; length of temporal fossa, 8.4'=">;* depth of temporal fossa, 4.3"". 



Habitat. — North Atlantic Ocean ; North Sea; Faroe Islands; Green- 

 land; coast of the United States, Cape Cod. 



* Eatlier large ; mean 7. 0""'", 



