THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 299 
Dorsal low, thick at the base, erect or somewhat falcate, with the anterior 
margin usually concave near the middle. 
Flukes broad, with convex anterior border, concave posterior border, and 
acuminate extremities ; posterior border crenate. 
Abdominal ridges converging in the median line below, anteriorly, forming an 
irregular projection below the symphysis of the mandible. 
Inferior outline of the body from the pudendum posteriorly broken by three 
convexities, of which the largest and most salient is behind the anus. Head and 
lips with numerous low rounded tuberosities; three rows on the head, one median 
and two lateral; a large irregular aggregation at the symphysis of the mandible 
and others scattered along the rami. A semi-elliptical furrow above the base of 
the pectoral. 
Color black, with white markings. Body black, with a varying number of 
white areas and markings on the lower surface, especially on the mandible, the 
abdominal ridges, and about the pudendum. Many of the smaller white markings, 
especially on the mandible, are in the form of complete or incomplete rings, or 
circular areas, and are due to barnacles. White markings occasionally on the 
upper jaw, behind the eye, and on the dorsal fin. Pectorals virtually all white on 
the upper surface, or with the basal one third to one half clouded with black; a 
narrow, irregular posterior border and the larger anterior sinuosities, when occu- 
pied by barnacles, black. Under surface entirely white. Flukes black above, with 
some white markings near the extremities; below, usually with a large white area 
on each side of the median line, bordered anteriorly and posteriorly with black. 
Whalebone dull grayish black, with some more or less dull whitish plates on 
the right side anteriorly. Bristles dull grayish black; the matted mass somewhat 
varied in tint. 
Skull very broad; rostrum obtuse, sides slightly convex. Outer margin of 
intermaxille sinuous. Nasals narrow, the anterior free margin acutely pointed. 
Orbital process of frontal triangular, very broad transversely; orbital margin 
narrow, oblique, the posterior angle extending out much farther than the anterior. 
Occiput narrow anteriorly. Coronoid process of mandible low. Vertebral for- 
mula: C. 7, D. 14, L. 11 (-10), Ca. 21. Total, 53 (-52). 
BaL@NOPTERA MuscuLUS (L.). 
Sulphurbottom. Plate 48, jig. 2. 
Form massive; size very large. Head very broad and obtuse. 
Average total length, 76 ft.; maximum, 89 feet. Pectorals, from head of 
humerus, 15 per cent. of the total length, faleate, obtusely pointed. Dorsal fin very 
small; its height about 1 per cent. of the total length; very variable in form, but 
usually more or less falcate; situated behind the line of the anus. 
Color of the body mottled gray throughout; the proportion of light and dark 
tints varying greatly in different individuals; head a little darker and nearly uniform ; 
body usually lightest at the shoulder and between the pectoral and navel; darkest 
