WHALES. 311 



are, prior to abrasion, the most prominent parts of the grinding 

 surface : they are, also, the first-formed parts of the molar, as are 

 the tubercles of the crown in true grinding teeth : like these tuber- 

 cles also, they are connected together at an early period of the 

 growth of the tooth, only by the vascular matrix, and in dried 

 specimens are separate and distinct. The subsequent conversion 

 of this apparently double into a bituberculate single grinder, is 

 produced by the progressive extension and confluence of the bases 

 of the tubercles, not by a process of sheding and the formation 

 of a new tooth, as Home conjectured. 



According to the analysis of Lassaigne, 99-5 parts of the dental 

 tissue of the Ornithorhynchus has the composition of horn, which is 

 hardened by 0-3 parts of the earthy matter of bone. 



The account of the horny dental apparatus of the Ornithor- 

 hynchus cannot be completed without a notice of the two short 

 and thick conical processes which project from the fore-part of the 

 raised inter-molar portion of the tongue, and w^hich, like the 

 before-mentioned more numerous spines on the corresponding part 

 of the tongue of the Echidna, represent in these low organized Mam- 

 mals the lingual teeth of Fishes. 



WHALES. 



132. Those Cetaceous Mammals which are properly called 

 Whales have no teeth, but horny substitutes in the form of plates 

 ending in a fringe of bristles, a peculiarity first pointed out by 

 Aristotle.(l) Of these plates, called " Baleen" and "Whalebone," 

 the largest, which are of an inequilateral triangular form, are 

 arranged in a single longitudinal series on each side of the upper 

 jaw, situated pretty close to each other, depending vertically from 

 the jaw, with their flat surfaces looking backwards and forwards 

 and their unattached margins outwards and inwards, the direction 



(1) The passage occurs in the 12th Chapter of the 3rd Book of the " Historia Animalium," 

 and has given rise to much speculation and controversy amongst the Commentators. " Mysti- 

 cetus etiam pilas in ore intus habet vice dentium, suillis setis similes." To a person looking 

 into the mouth of a stranded whale, the concavity of the palates vt^ould appear to be beset with 

 coarse hair. The species of Balcenoptera which frequents the Mediterranean might have afforded 

 to the Father of Natural History the subject of his philosophical comparison. 



