4 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



Order B.-HYPEROTRETA. 



{The Myxinoid Fishes.) 



Kostril 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 provided with threads for adhesion. Marine lamprey -like animals, 

 burrowing into the flesh of fishes, on which they feed. 



There is but one family, Myxividw, unless we assign separate rank to 

 Bdellostoma on account of the difference in the gill-openings. {uKspwa^ 

 palate; rprjzu^, perforate.) (Family Myxinidce Giinther, 510-512.) 



Family II— MYXINID.E. 



{The Hag- fishes.) 



The characters of the family are included above. Genera two ; species 

 few ; marine animals, found in all temperate seas. {Myxinidw Giinther, 

 viii, 510-512. 



* Branchial apertures on^ on eacli side, leading by six dncts to six brancliial sacs. 



Myxine, 2. 



** Branchial apertures six or more on each side, each leading directly to a branchial 



sac Bdellostoma, 3. 



2.— MYXIIVE LiuntBUS, 1758. 



Hag-fishes. 



(Linuajus, Systema Naturae : typo Myxbie glutUiosa L.) 



Body eel-shaped, covered by a thin skin, which is easily detached. 

 Along the lower side, for nearly the whole length of the animal, are 

 two rows of mucous glands, each with an external opening, from which 

 exudes a quantity of mucus which renders these animals during life 

 excessively slimy. No 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 



