HISTORY OF MARINE MAMMALS—ABEL. ANQ5 
pectoral fin, or flipper, is long and narrow, and has only four fingers. 
There are but two furrows on the underside of the body. 
Third family, rorquals (finbacks and humpbacks).—To this group 
belong the gigantic blue whale, or sulphurbottom, previously men- 
tioned (fig. 1); the humpback (J/egaptera nodosa Bonn.), 17 meters 
(55% feet) long (fig. 3); the common finback (Balenoptera physa- 
fus L.), which has a length of about 23 meters (755 feet) ; and the 
little piked whale (Balenoptera acuto-rostrata Lac.), which is only 
9 or 10 meters (295 to 32$ feet) long. 
The humpback (fig. 3) reminds one of the bowhead, on account 
of its turgid body, but differs from the latter both as regards its 
flipper, or pectoral fin, which is long, narrow and four-fingered, 
and measures almost one-third the total length of the body, and 
also on account of the presence of a small dorsal fin and of numerous 
furrows in the belly. . 
Fig. 5.—Humpback (Megaptera nodosa Bonn.). Length reaches 17 meters (552% feet). 
After F. W. True. The skin is covered with numerous parasites, in the form of closely 
clinging barnacles. 
The sulphurbottom, common finback, and little piked whale are 
much more slender than the humpback, and have decidedly shorter 
flippers. The hand of the finbacks and humpbacks is four-fingered, 
owing to the disappearance of the middle finger. 
The cervical vertebre are separate in the finbacks, humpbacks and 
gray whale, but in the right whales are fused together, forming a 
compact, immovable mass. 
B. TOOTHED WHALES. 
The second group of living cetaceans is distinguished from the 
edentulous whalebone whales by the possession of teeth. In the 
whalebone whales there as many as 51 denticles in each jaw, but only 
in the early stages of embryonic life. They disappear long before the 
birth of the animal. 
No toothed whale reaches the size of the sulphurbottom, but the 
male sperm whale (Physeter macrocephalus lL.) is 18 meters (59 feet ) 
long. The female is only half as long. The lower jaw of the sperm 
