Rhinochimaeridae
by M. Stehmann and D. L. Burkel
Body elongate and tapering to a point, sometimes with a filament at end of tail. Males with a thumb-like retractable appendage on midfront of head and a pair of retractable similar appendages in front of pelvic fins. Snout very long and pointed with a broad flexible rostrum; nostrils large, immediately before mouth; a single large gill-opening, covered by an operculum-like flap on each side; a system of easily seen mucous canals and sensory pores on head. Mouth underneath; two pairs of large cutting tooth-plates above and one pair below. Two dorsal fins, the first triangular, with a large, stiff movable spine in front, the second separated from it and long and low; anal fin present or absent; caudal fin lanceolate, with or without a filament, upper edge a crest of denticles in Rhinochimaera. Males with simple rod-like claspers. Skin smooth and slippery, except for denticles on male organs (and part of upper midline in early juveniles).
Pelagic to benthopelagic in deepwater from about 360 m to 2,600 m, probably also deeper; rare to moderately common, depending on species; behaviour and food probably as in Chimaeridae. Oviparous; egg-capsules large and tadpole-shaped, with an anterior constriction, a long posterior tube and very wide lateral membranes with many transverse ribs.
Genera 3; in Clofnam area 2.
Recent revisions: Bigelow and Schroeder (1950), Bigelow and Schroeder (1954 on a regional basis), Karrer (1972).