Fig. 319.—Ovum of Myxine glutinosa, enlarged.
The fishes of this family are known by the names of “Hag-Fish,” “Glutinous Hag,” or “Borer;” they are marine fishes with a similar distribution as the Gadidæ, being most plentiful in the higher latitudes of the temperate zones of the northern and southern hemispheres. They are frequently found buried in the abdominal cavity of other fishes, especially Gadoids, into which they penetrate to feed on their flesh. They secrete a thick glutinous slime in incredible quantities, and are therefore considered by fishermen a great nuisance, seriously damaging the fisheries and interfering with the fishing in localities where they abound. Myxine descends to a depth of 345 fathoms, and is generally met with in the Norwegian Fjords at 70 fathoms, sometimes in great abundance.
Myxine.—One external branchial aperture only on each side of the abdomen, leading by six ducts to six branchial sacs.
Three species from the North Atlantic, Japan, and Magelhæn’s Straits.
Fig. 320.—Myxine australis. A, Lower aspect of head; a, Nasal aperture; b, Mouth; g, Branchial aperture; v, Vent.
Bdellostoma.—Six or more external branchial apertures on each side, each leading by a separate duct to a branchial sac.
Two species from the South Pacific.
FOURTH SUB-CLASS—LEPTOCARDII.
Skeleton membrano-cartilaginous and notochordal, ribless. No brain. Pulsating sinuses in place of a heart. Blood colourless. Respiratory cavity confluent with the abdominal cavity; branchial clefts in great number, the water being expelled by an opening in front of the vent. Jaws none.