WHALEBONE WHALES. Ill 



may be added the lack of a distinct coronoid process to the jaw. The two genera are usually 

 grouped in a distinct family, the Balaenidae. 



The genera Balaenoptera (Finback Whales) and Megaptera (Humpbacks) are less closely 

 related to the two genera preceding than to each other and are united to form a distinct family 

 (Balaenopteridae) . They agree in having the rostral part of the skull broad at the base, and 

 tapering toward the snout, without the great arching seen in Balaena and Eubalaena; the 

 number of fingers is reduced to four, the throat is grooved by numerous longitudinal folds for 

 the expansion of the great gular bag, and there is an adipose fin (often poorly developed 

 in Megaptera) at the lower part of the back. All the neck vertebrae, in addition, are practically 

 free, or at most some of them are slightly fused by the tips of theii- processes, and there is a 

 prominent coronoid process on the lower jaw. Megaptera presents a curious combination of 

 characters, specialized and unspecialized, as compared with Balaenoptera. Its chief distinctive 

 features are its greatly developed pectoral limb, of extraordinary length, and the loss of acro- 

 mion and coracoid, the two processes of the shoulder blade. In respect of these points, it 

 surpasses Balaenoptera in specialization. On the other hand it shows a less degree of develop- 

 ment in its short body, the small number of throat folds, and the many hairs on the head- 

 The dorsal fin is of somewhat less definite form also. 



The third family of baleen whales (Rhachianectidae) is represented by but a single living 

 species, the California Gray Whale (Rhachianectes glaucus), confined to the North Pacific. 



Whalebone Whales of New England. 



Of the four genera of baleen whales known from the North Atlantic, Balaena — with its 

 single species B. mysiicetus, the Bowhead or Greenland Whale — seems entirely confined to 

 Arctic waters, and though it formerly followed the cold current from Baffin's Bay south into 

 the St. Lawrence Gulf, it is unlikely that it reached New England within historic times. Of 

 the three remaining genera, Eubalaena and Megaptera are represented north of the equator 

 by a single species each, and Balaenoptera is accredited with four. All of these six species 

 have been ascertained to occur within the New England limits. They are seen occasionally 

 in the near-shore waters but more often at a distance of some miles from land; or dead ones 

 from time to' time are cast ashore by the tide. 



Of these six living species occurring in the North Atlantic Ocean, closely allied if not identi- 

 cal representatives are now known from the South Atlantic and from the Pacific Oceans. 

 Separate names have been given them by naturalists, so that a multiplicity of species is now 

 nominally recognized, where in all probability there is practical identity. The late Sir William 

 Turner, an eminent authority on whales, has lately (1913, 1914) stated his belief that all these 

 species are cosmopolitan, and this indeed seems likely to prove the case. Until this can be 



