7. LAGENORHYNCHUS L. ACUTUS. 169 



LAGENORHYNCHUS ACUTUS Gray. 

 (Plate 23, figs. 1 aud 2.) 



Form stout; greatest girth of the body anterior to the midille 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. Ou the upper part of the sides of the tail the gray color passes 

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

 oblong area of white. A narrow black band 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 

 flukes inferiorly and the adjacent margin of the tail are whitish. The 

 margin of tlie lower jaw is sometimes black. 



Teeth g. Vertebra'. : C. 7, D. 15, L. 19 , Ca. 39=80. Skull broad 

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

 sivull. Proximal expanded portion of the maxilhe broad (breadth 

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

 Preinaxilhe flat, their outer margin sinuate. Temporal fossa) elongate 

 and extending obliquely upward. Pterygoid bones in contact; large, 

 with lateral keels and obtuse crests, the posterointernal free edge 

 transverse and not strongly eraarginate; vomer appearing in the 

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

 slip of the iutennaxilhp, which extends thence along the distal half of 

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



Measurements of the exterior {from Dugmd).—Tot-^\ length (along 

 the back), 99 inches (251.5'^'"); extremity of snout to pectoral fin, 16 

 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 (G3.5'"'). 



Measurements of the sJcull.—{JJ. S. ^N'atioual Museum, 1421:4, Cape 

 Cod). Total length, 42.5"" ; length of rostrum, 21.6'" ; breadth of ros- 

 trum at base, 11.4'"; at its middle, 7.6 " ; breadth between orbits, 

 21.6"'^; length of temporal fossa, 8.4"" ;* depth of temporal fossa, 4.3"". 



Srt&jfa/.— North Atlantic Ocean; North Sea; Faroe Islands; Green- 

 land; coast of the United States, Cape Cod. 



* RatUcr large ; meau 7.9''"'. 



