THE SEAL-TOOTHED WHALES. 247 



remaining vertebrae, tapering to exceedingly small bones in the tail, are each separated by thick elastic 

 fibro-cartilaginous cushions, thus giving great flexibility behind. The breast-bone is often in a single 

 flat piece. The skull is greatly modified and by no means uniform throughout the group. Among 

 the Dolphins and others (Delphinidse) it is strangely distorted, so that the one side does not agree 

 with the other. The upper jaw-bones (maxillce) and the pair of bones above and between them 

 (premaxillcK) are unusually produced, and this production in front, with corresponding extension of 

 lower jaw, gives a lengthened facial region and snout accordingly. The bones surrounding the occiput 

 and brain-pan are directed upwards, the former occasionally forming a great horseshoe crest. The 

 bony nasal passages instead of coming forward lead nearly direct upwards towards the summit of the 

 cranium, nasal bones themselves being all but absent. The orbits are often small and open behind. 

 Curiously enough, though deficient in ears, the interior tiny ear-bones of other Mammals are in the 

 Whales great massive structures and exceedingly dense, so much so that they are frequently preserved 

 fossil when other osseous structures are destroyed. 



Cetacea have been a troublesome group to unravel, being ocean-dwellers, and many of them huge 

 brutes. To study them in the live state has been difficult, and their carcases when captured or stranded 

 on shore are as unmanageable for purposes of examination. As to their classification the two sub- 

 orders Denticete, Toothed Whales, and Mysticete, Whalebone Whales are universally accepted. As 

 regards the families, the main groups are tolerably well agreed upon, though differently named by 

 authorities. Among the sub-families, the genera and the species, there is less unanimity. The 

 grouping of the living forms proposed by Professor Flower is in Great Britain more frequently 

 adopted, while MM. Gervais and Yan Beneden, in their great work on " Osteographie des Ce'taces," 

 have collated the living and fossil forms. Some species and genera of Whales are restricted within 

 given areas, as are the Seals, but of the habitat of many others in truth so little is known that no 

 defined limit can be assigned. The great majority are migratory ; some are gregarious, others more 

 solitary in disposition. A few are quite fluviatile ; but most are found in the high seas. Following 

 the above primary divisions, we give precedence to 



THE TOOTHED WHALES (DENTICETE.) 



Except the possession of teeth, no other available common character need here be given. 



THE SEAL-TOOTHED WHALES (PHOCODONTIA OR ZEUGLODONTIA). 



We begin with these, as they are supposed by some authorities to be intermediate between the 

 Seals and Whales. This extinct family, judging from the various mutilated remains found, comprised 

 several different 

 genera. The most 

 notable of these 

 are Zeuglodon, 

 Squalodon, and 

 Phocodon. The 

 ZEUGLODONS may 

 have attained a 



RESTORATION OF SKULL (A). AND TOOTH (B) OF ZEUGLODOX. (After Gaudru.) 



length of fifty or 



sixty feet. Their vertebral column was cetacean in character, but the neck-bones were separate, 

 though considerably flattened from before backwards. Some assert that their skull bore resem- 

 blances to that of the Seals in several respects. Their brain-cavity undoubtedly was remarkably 

 small, and relatively less than that of known Whales ; but the supposed Seal-like skull structure 

 is open to question. The teeth were of two kinds : those in front being conical, pointed, and 

 lengthened; and those behind laterally compressed, serrate, and double-rooted. The dental 

 formula is stated to have been Incisors, |=| ; canines, ^ ; molars, || = 36. Hind limbs may 

 have been absent, but the fore limbs suggest rather than furnish precise data showing approxi- 

 mation to the Seals. The SQUALODONS are known chiefly from the skull, which, as a whole, has 

 strong resemblances to those of the curious Amazon Dolphins, called Inia and Pontoporia, but the 

 dentition, however, agrees rather with that of the Dolphin of the Ganges, Platanista. They possessed 



