394 



ZOOLOGY. 



The lampreys (Fig. 409) constitute the principal type of this 



group. 



506. A very singular animal, evidently belonging to the 

 vertebrata, but deficient in many of 

 their characters, has lately attracted 

 some attention. It is called the 

 amphioxus, and is a small marine 

 animal, sufficiently like a fish, but 

 which has neither vertebrae properly 

 so called, nor heart, nor red blood, 

 nor a distinct brain. Its skeleton is 

 represented by a cartilaginous stalk, 

 resembling the cartilaginous cord 

 preceding the formation of the 

 vertebral column in the embryo 



of the ordinary vertebrata ; the cerebro- spinal axis occupies 



its usual place, but presents anteriorly no enlargement which 



Fig. 408. Mouth of the 

 Lamprey. 



Fig. 409. The Lamprey. 



may be compared to a brain ; the circulation is accomplished 

 by means of vessels whose walls are contractile, and the walls 



Fig. 410. The Gourami.* 



* A valuable fish, now being acclimatized in France ; it comes originally 

 from China and some Asiatic rivers. It was first introduced into the Isle of 

 France. E. K. 



