448 CYCLOSTOMATA 



be noted perhaps that the variability is really much greater than 

 is indicated, for there are many variations in anatomical detail 

 apart from numbers. 



There is no doubt that the slime so abundantly secreted is 

 protective. It flows out copiously in viscid threads when the 

 hag is excited, and it forms a slippery sheath which makes 

 it difficult for one to grip the animal. 



Different Kinds of Myxinoids 



Myxine. — In the genus Myxine there are not more than six 

 pairs of gill-sacs, which have a common external aperture on 

 each side. The genus is represented in the Atlantic, the North 

 Sea, and the Pacific. The North Sea species is Myxine 

 glutinosa, which may attain a length of nearly 2 ft. The 

 North American form is sometimes distinguished as M. limosa. 



Paramyxine. — In the genus Paramyxine, from the Pacific, 

 the connection of the gill-sacs with the exterior is intermediate 

 between that in Myxine and that in Bdellostoma. 



Bdellostoma. — In the genus Bdellostoma from the Pacific 

 e.g., off California and Chili, there are six to fourteen pair of 

 gill-sacs, all opening separately. The common Californian 

 species, which has been most studied, is B. dombeyi. 



