MYXINOIDS OR HAG-FISHES 445 



these are generally fishes which have been caught on the hooks 

 of a long line, and were probably bored into after they had 

 been hooked. It has been generally thought that the hags 

 could not fasten on to a free swimming fish, they have no 

 sucker as the lamprey has, and the teeth are not suited for 

 gripping. 



In Japan, however, Bashford Dean found that a species of 

 hag common there frequently made its way into a floating cage 

 and attacked and killed the living fish or squid contained in it. 

 Hags are thus almost certainly able to attack living, active 

 fishes in nature, but they are not parasites because they do not 

 live for any considerable time within the living fish, the latter 

 being killed by their attack. 



The eggs are sausage-shaped, yellow in colour and about 

 an inch in length. At each pole are a number of thread-like 

 processes of the horny envelope, ending in triangular knobs, 

 and these threads become entangled together so that the 

 eggs laid at one time are connected together in a sort of string 

 or chain. Mr. J. T. Cunningham showed in 1885 that the 

 envelope with its threads was formed entirely in the ovary, not 

 in an oviduct as is the case of Dog-fishes, since oviducts are 

 entirely absent. He also showed that Myxine was usually 

 hermaphrodite, the posterior end of the generative organ being 

 male, the anterior end female, but both parts are not ripe at the 

 same time. The same is not the case, according to the observa- 

 tions of Professor Bashford Dean, in the Californian hag, 

 Bdellostoma stonti. In that species, although the structure of the 

 organ is similar, the male and female parts are developed in sepa- 

 rate individuals. Very few of the eggs of the European 

 Myxine have been obtained, in spite of persistent endeavours, 

 but Professor Bashford Dean was successful in obtaining con- 

 siderable numbers of the fertilised eggs of the Californian hag. 

 They were brought up by Chinese fishermen entangled on the 

 hooks of ling lines. Professor Bashford Dean has published a 

 fairly complete account of the development of the embryo within 

 the egg up to the time of hatching. 



The newly hatched animal (about 2\ in. in length) has 

 the same shape as the adult. There is a marked increase in 

 girth when about 15 inches long, but this does not seem to 

 be connected with sexual maturity. The growth, like the de- 



