170 The Cyclostomes, or Lampreys 
Of Myxine, numerous species are known—Myxine glutinosa, 
in the north of Europe; Myxine limosa, of the West Atlantic; 
Myxine australis, and several others about Cape Horn, and 
Myxine garmani in Japan. All live in deep waters and none 
have been fully studied. It has been claimed that the hagfish 
is male when young, many individuals gradually changing to 
female, but this conclusion lacks verification and is doubtless 
without foundation. 
In the Eptatretide the gill-openings, six to fourteen in number, 
are externally separate, each with its own branchial sac as in 
the lampreys. 
The species of the genus Eptatretus (Bdellostoma, Heptatrema, 
and Homea, all later names for the same group) are found only 
in the Pacific, in California, Chile, Patagonia, South Africa, and 
Japan. In general appearance and habits these agree with the 
species of Myxine. The species with ten to fourteen gill-openings 
(dombeyt: stoutz) are sometimes set off as a distinct genus (Polis- 
totrema), but in other regards the species differ little, and fre- 
quent individual variations occur. Eptatretus burgeri is found 
in Japan and Eptatretus forsterit in Australia. 
The Hyperoartia, or Lampreys.—In the order Hyperoartia, or 
lampreys, the single nostril is a blind sac which does not pene- 
trate the palate. The seven gill-openings lead each to a sepa- 
rate sac, the skin is not especially covered with mucus, the eyes 
are well developed in the adult, and the mouth is a round disk 
armed with rasp-like teeth, the comb-like teeth on the tongue 
being less developed than in the hagfishes. The intestine in 
the lampreys has a spiral valve. The eggs are small and are 
usually laid in brooks away from the sea, and in most cases the 
adult lamprey dies after spawning. According to Thoreau, “it 
is thought by fishermen that they never return, but waste 
away and die, clinging to rocks and stumps of trees for an in- 
definite period, a tragic feature in the scenery of the river-bottoms 
worthy to be remembered with Shakespeare’s description of 
the sea-floor.” This account is not far from the truth, as re- 
cent studies have shown. 
The lampreys of the northern regions constitute the family 
of Petromyzonide. The larger species (Petromyzon, Entosphenus) 
live in the sea, ascending rivers to spawn, and often becoming 
