AGNATHA 



543 



any trace of paired limbs. For convenience lampreys and hagfishes 

 may be put together in the class Cyclostomata, but it is at least 

 possible that they are descended from different fossil classes. 



Lampetra fluviatilis, the river lamprey, is tolerably common 

 in some rivers, such as the Severn, and Myxine gliitinosa, the 

 hagfish, is found in British seas. The larva of lampreys, the 

 * ammoccete ', has a ciliary method of feeding comparable to 

 that of Branchiostoma. 



