300 THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 



between the navel and anus ; some entirely white spots on the posterior ends of the 

 abdominal lidges. 



Pectorals ^ray on the upper surface except at the tij), usually with some 

 lighter blotches ; white ou the lower surface, anterior margin, and tip. Dorsal fin 

 dark gray, usually with whitish center crossed by light vertical, curvilinear markings. 

 Flukes gray above and below ; the lower surface with fine light and dark gray lines 

 running antero-posteriorly. 



Whalebone entirely black. 



Rostrum of the ci'aniuin very broad; free margin of maxillae convex ; nasals 

 oblong, with ti'uncated anterior mai-giu. Vertebral formula: C. 7, D. 15 (-16), 

 L. 14 (-16), Ca. 26 (-28). Total, 63-65. 



BALiENOPTERA PHYSALUS (L.). 



Common Finback. Plate 4-8, jig. 1. 



Form remarkably slender, size large. Head narrow and pointed. 



Average total length, 59 feet ; maximum, 81 or 84 feet (?). 



Pectorals, from head of humerus, 12 per cent, of the total length, lanceolate, 

 pointed. Dorsal fin moderate; its height about 2-|^ per cent, of the total length; 

 moi'e or less falcate ; situated just posterior to line of anus. 



Color of the body dark gray above, white below ; the two colors mei-ging by 

 imperceptible gradations on the flanks. Coloration of the head not bilaterally 

 symmetrical, there being more white on the i-ight side than on the left, at least as 

 far back as the pectoral ; right ramus of the mandible white externally, and also 

 the anterior third, or more, of the whalebone; left ramus of the mandible and left 

 whalebone dark gray. Dorsal fin dark gray like the back. Pectorals gray on 

 dorsal sui'face, white on ventral sui'face and antei-ior margin. Flukes dark gray 

 above, white below, with gray posterior margin. Gray of the flanks extending 

 obliquely downward and backwai'd from the pectorals toward the flukes, but not 

 reaching the inferior margin of the caudal peduncle, where there is a narrow white 

 edge, bounded anteriorly by a linear gray mai'k directed obliquely forward and 

 downward toward the anus. 



Whalebone gray striped longitudinally with yellowish white in varying pro- 

 portions; anterior whalebone on right side of body all yellowish white. 



Rostrum of the skull narrow and acuminate ; free mai-gius of maxillas nearly 

 straight. Nasals narrow, and pointed anteiiorly in the median line. Vertebral 

 formula: C. 7, D., 15 (-16), L. 14 (-15), Ca. 25 (-26). Total, 61-63. 



Balenoptera borealis Lesson. 



Pollack whale. Plate 49, Jig. S. 



Form moderately robust. Size moderate. Average total length, 46 to 47 feet ; 

 maximum, 54 feet. Pectorals, from axilla, 11 per cent, of total length, slender and 

 pointed. Dorsal large, high, and falcate ; vertical height about 4 [)er cent, of the 

 total length ; situated just anterior to the line of the anus. 



