CHAPTER LXVHI 



LOWEST CLASSES OF VERTEBRATES 



THERE arc a few creatures which, by reason of their 

 internal skeletons and jointed back-bones, are justly 

 entitled to stand with the vertebrates, but yet are lower in 

 the scale than the lowest fishes. For these it has been neces- 

 sary to create two grand divisions of the first rank; and they 

 stand as two small and very low Classes. It is because of 

 their very low position in the zoological scale of vertebrates 

 that it becomes important to know them. 



THE LAMPREYS 



Class Marsipobranchii 



A Lamprey is an aquatic creature which bears so strong 

 a resemblance to an eel that for a long period all Lampreys 

 were regarded as true eels. Even to-day the most important 

 of our species is, by unscientific persons, almost universally 

 called the "Lamper Eel." In view of the general external 

 resemblance of these creatures to eels of similar size, it is not 

 strange that their true character remained for a long period 

 quite unknown. As a matter of fact, these creatures forcibly 

 illustrate the unwisdom in animal classification of attaching 

 too much importance to external characters. 



The lampreys are the lowest and last creatures that have the 

 spinal cord expanded at its upper end into a brain and encased 



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