-502 Canadian Record of Science. 



similar in external appearance, and may be distinguished only by their 

 internal anatomy. A striking example of this is the mole, which has 

 taken to a burrowing existence. Moles, be they insectivorous, rodent, 

 or marsupial, have assumed a character adapted to their subterraneous 

 existence. A coat of spines lends resemblance to other members of 

 the same class of animals. Thus the author shows that though certain 

 animals may resemble one another very closely in external appearance, 

 as the burrowing animals, or may possess certain peculiar structural 

 features, as tusks, they may not be internally related, and the simi- 

 larities of form and structure must therefore have been independently 

 acquired, and not inherited from a common ancestor. These so-called 

 • accidental resemblances indicate what may be termed parallel develop- 

 ment, or, to be brief, "parallelism." This parallelism is exemplified 

 in respect to teeth and dentition, and to the elongation of the limbs. 

 The resemblances between Unintatheres and Protoceras are clearly due 

 to parallel development. 



Cestaceans next claim attention. Existing Cestaceans are divisible 

 into the two groups — Whalebone Whales and Toothed Whales ; differ- 

 ing, as the name implies, in the presence or absence of true teeth. 

 Whether these two groups have been derived from a common ancestral 



■ stock, or have had a totally independent origin, is as yet undecided. 

 The discovery in Patagonia of certain toothed whales that have nasal 

 bones nearly as well developed as is the case in whalebone whales, 



■ removes one of the difficulties in regarding the latter as descended 

 from the former. Be that as it may, they are extremely ancient, and 

 have undergone parallel development. That the whalebone whale has 

 been developed from an ancestor provided with a full series of functional 

 teeth is proved by the fact that their young, in an early stage of 

 development, are provided with teeth germs, which are absorbed by 



■ the gum prior to birth. As might be expected, closely associated with 

 the function of rumination is the complexity of the molar teeth, known 

 as selenodont structure. True ruminants, or chewers of the cud, pos- 

 sess hoofs, a cannon bone in both limbs, and no upper front teeth. 



The tallest of all quadrupeds owes its towering stature to the 

 lengthening of two of the bones of the leg and of the vertebra? of 

 the neck. In delegating to the giraffe the position it should take 

 among mammals, especial notice must be taken of its three bony horns, 



■ covered with skin, and which are quite unlike those of any other rumi- 

 nant. Were it not for certain bodily peculiarities, the "ship of the 

 desert" might find in the giraffe a formidable rival as a beast of 

 burden, since the latter is better adapted to life in desert places, and 

 can live much longer without water. Though in the Pliocene period 

 the giraffe roamed over Southern Europe and Asia, at the present day 

 it is confined to Eastern and Central Africa; and unless care be taken 

 this unique animal will soon suffer extermination — shot by the relent- 

 less hunter solely for the paltry sums brought by the skins. 



