18 CALIFORNIA MAMMALS. 



rels; number of folds on belly 26, averaging four to six inches 

 in width. These folds, which extend from the anterior portion, 

 of the throat over the belly, terminating a little behind the pec- 

 torals, are capable of great expansion and contraction, which en- 

 ables the Humpback, as well as the other rorquals, to swell their 

 maws when food is in abundance about them. It is proper to 

 state that the skull and upper jaw bone of any ordinary sized 

 animal would be about 15 feet long by 6 broad. 



"The usual color of the Humpback is black above, a little 

 lighter below, slightly marbled with white or gray ; but sometimes 

 the animal is of spotless white under the fins and about the 

 abdomen. The posterior edge of the hump, in many animals, is 

 tipped with pure white. 



"The Megaptera varies more in the production of oil than 

 all others of the rorquals. We have frequently seen individuals 

 which yielded but 6 to 10 barrels of oil, and others as much as 

 75. Most of this variation may be attributed to age or sex. 



"Like all other rorquals it has two spiracles, and when it re- 

 spires the breath and vapor ejected through these apertures form 

 the 'spout,' and rise in two separate colums, which, however, unite 

 as they ascend and expand. When the enormous lungs of the 

 animal are brought into full play the spout ascends twenty feet or 

 more. When the whale is going to windward, the influence of 

 the breeze is such that a low bushy spout is all that can be seen. 

 The number of spouts to a 'rising' is exceedingly variable ; some- 

 times the animal blows only once, at another time up to 15 or 

 :20 times. 



"Although the Humpback is found on every sea and ocean, 

 our observations indicate that they resort periodically, and with 

 some degree of regularity, to particular localities, where the fe- 

 males bring forth their young. It seems, moreover, that both 

 sexes make a sort of general migration from the warmer to 

 the colder latitudes, as the seasons change. They go north in 

 the northern hemisphere as the summer approaches, and return 

 50uth as winter sets in. 



