MAMMALIA. 421 



of whales, and there is a great difference of opinion upon this subject 

 among naturalists. This is very natural, as these great cetaceans are 

 seldom met with by practical observers, and come ashore at periods of long- 

 intervals only. Moreover, they cannot be compared directly with one 

 another ; and their remains cannot be easily preserved, nor their forms 

 easily reproduced correctly in drawing. 



Of the genus Balceno2:)tera, three species seem to be well characterized ; 

 B. jubartes, the rorqual, from the northern Atlantic, and from seventy to 

 eighty feet in length; B. onusculus, from the Mediterranean, and B. ant- 

 arctica, from the Cape of Good Hope. Some other species are cited as 

 belonging to the northern seas, but are not satisfactorily described, such as 

 B. gibbar, seen between Cherie Island and Nova Zembla, B. acuto-rostrata, 

 or sharp nosed whale, inhabiting chiefly the Norwegian seas. 



The genus Baltena differs from the preceding by its great, thick, and 

 obtuse head, in being deprived of the fin-like expansion of the back, and 

 in having the inferior part of the body smooth, that is to say, deprived of 

 the longitudinal folds, more or less deep, as seen in Baltenoptera. A single 

 species of this genus is adopted by some authors, B. mysiicetiis, or black 

 common Greenland whale (j^l. 106, Jig. 1), the one constituting the chief 

 object of the whale fishery. The head forms one third of the total length. 

 The broad jaw extends along the whole length of the head to behind the 

 s^ll eyes. The oesophagus is narrow, for which reason the whale can 

 swallow small marine animals alone. The color is velvet black, marbled 

 with grey and white ; the belly is entirely white. It would be highly 

 interesting to know whether the same species of whale be found in all the 

 fishing grounds, a question which we may be authorized to doubt, as we 

 have some accounts and some facts which indicate a second species around 

 the Cape of Good Hope, B. antarctica differing from B. mysticetus in some 

 peculiarities in the structure of the bony head. We are told also, that the 

 ice-whale, or B, islandica, differs from B. mysticetus in having a more 

 lengthened body, and a proportionally smaller head. The two spiracles or 

 air holes represent two small semicircles, which are a little separated from 

 each other, the convexities of which are opposed. The eye is very small, 

 and its shortest diameter is placed obliquely. The general color of B. 

 islandica is grey, more or less distinct in its shades. The lower part of 

 the head often appears like a great oval of very shining white, at the centre 

 and circumference of which are seen grey or black spots, irregular and 

 confused. 



Several fossil species of Baltena and Bafenoptera have been found in 

 the tertiary deposits of Europe. The genus Cetotherium is extinct ; its 

 remains have been found in the upper tertiary of Eussia, and assimilated 

 at first to other cetaceans, when the present genus was established and 

 placed in the vicinity of Baltenoptera, from which it differs by the broad- 

 ness and flatness of the posterior part of the skull, the elevated and thick 

 arch, and the deep temporal grooves. C. raihhei is the only species known 

 and found in several localities in the Eussian empire. 



Balccna mysticetus, Greenland or right whale, is most frequently found 



ICONOGRAPHIC ENCYCLOPEDIA. — VOL. II. 40 025 



