80 THE CAtflKE TEET7T. 



larger bead than the female, and it no doubt aids these 

 animals in their aquatic battles. Lastly, the adult 

 male ornithorhyn'chus is provided with a remarkable 

 apparatus, namely, a spur on the foreleg, closely re- 

 sembling the poison fang of a venomous snake. Its 

 use is not known, but we may suspect it serves as a 

 weapon of offense. It is represented by a mere rudi- 

 ment in the female." * 



The foregoing extracts would not be complete with- 

 out giving the views of this great disciple of evolution 

 concerning the same teeth in man. He says (" Descent 

 of Man," vol. i, p. 198) : 



" We have thus far endeavored rudely to trace the 

 genealogy of the vertebrata by the aid of their mutual 

 affinities. "We will now look to man as he exists, and 

 we shall, I think, be able partially to restore during 

 successive periods, but not in due order of time, the 

 structure of our early progenitors. This can be effected 

 by means of the rudiments which man still retains, by 

 the characters which occasionally make their appear- 

 ance in him through reversion,! and by the aid of the 

 principles of morphology and embryology. J The early 



* For further information concerning this strange animal see 

 the " Vocabulary." 



f " The occasional appearance at the present day of canine 

 teeth which project above the others, with traces of a diastema 

 or open space for the reception of the opposite canines, is in all 

 probability a case of reversion to a former state, when the pro- 

 genitors of man were provided with these weapons." "Descent 

 of Man," Vol. II, p. 300. 



\ " The human em'bryo resembles in various points of struc- 

 ture certain low forms when adult. For instance, the heart at 

 first exists as a simple pulsating vessel ; the excreta are voided 

 through a cloacal passage, and the os coccyx projects like a true 



