Hooks: 8-9; anterior teeth: none; posterior teeth: 17-22.
Maximum adult body length: 23 mm; tail: 26-34 %.
Body flabby, broadest at region of tail septum; transversal musculature on trunk; head wide; hooks serrated in juveniles. One pair of very long lateral fins both on trunk and tail; lateral fins partially rayed, rounded. Gut diverticula absent; fairly large eyes without pigment. Seminal vesicles conical; position of seminal vesicles: touching neither posterior fins nor tail fin. Ovaries long, reaching to neck region, curved in juveniles; ova large. Adhesive papillae and adhesive organs absent; apical glands present.
Distribution: deep-mesopelagic to bathypelagic; (probably) very wide
Remarks: found below 350 m in the North Pacific; loose collarette-like tissue around body from ventral ganglion to tail septum.
Type locality: off coast of California.