4 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
Order B.-IIY1‘ER0TRETA. 
{The Myxinoid Fishes.) 
Xostril tube-like, with cartilaginous rings, penetrating the palate, its 
position at the extremity of the head, over the mouth snout with eight 
barbels ; mouth without lips ; one median tooth on the palate and two 
comb-like series of teeth on the tongue. Branchial apertures at a great 
distance from the head ; a series of mucous sacs along each side of the 
abdomen. Intestine without spiral valve. Eggs large, with a horny 
case provi<led with threads for adhesion. Marine lamprey-like animals, 
burrowing into the flesh of fishes, on which they feed. 
There is bnt one family, 2iyxini(Ia’, unless Ave assign separate rank to 
Bdellostoma on account of the difference in the gill-openings, {urzepwa, 
palatej zprjzdr, perforate.) (Family Myxinidce Gunther, 510-512.) 
Family II.— MYXINID^. 
{The Hay-fishes.) 
The characters of the family are included above. Genera two; species 
feAv ; marine animals, fonnd in all temperate seas. {Myxinidce Giinther, 
Aflii, 510-512. 
* Brancliiiil apertiii’es one on each side, leading by six ducts to six branchial sacs. 
Myxine, 2. 
** Branchial apertures six or more on each side, each leading directly to a branchial 
sac Bdellostoma, 3. 
2. — MYX5I\E Linnajus, 1758. 
Hay-fishes. 
(Linnaeus, Systema Naturae : type ]ilyxine glutinosa L.) 
Body eel-shaped, coA^ered by a thin skin, which is easily detached. 
Along the lower side, for nearly the whole length of the animal, are 
tAvo rows of mucous glands, each with an external opening, from which 
exudes a quantity of mucus Avliich renders these animals during life 
excessiA'cly slimy. Xo eyes. Brain small, of the normal fish type. 
Skull little developed, cartilaginous; the flexible notochord enclosed in 
its sheath, and extending from the base of the skull to the end of the 
