Author: Bigelow and Schroeder, 1941
Field Marks:
Dwarf, tadpole-like scyliorhinids with huge heads and slender bodies, first dorsal origin somewhat anterior to pelvic origins.
Diagnostic Features:
Body strikingly tadpole-shaped, head expanded but trunk and tail slender and cylindrical, tapering to caudal fin; body very soft, semigelatinous, and thin-skinned, with weakly calcified dermal denticles; stomach not inflatable; tail short, length from vent to lower caudal origin less than half of snout-vent length. Head enlarged and considerably depressed, narrowly rounded in lateral view and not wedge-shaped; head very long, about 1/3 of total length in adults; snout very short, less than half of mouth width, thick, and flattened, bluntly pointed in lateral view; snout not expanded laterally, broadly rounded in dorsoventral view; ampullal pores not greatly enlarged on snout; nostrils of moderate size, with incurrent and excurrent apertures only partly open to exterior; anterior nasal flaps broadly triangular, without barbels, well separate from each other and falling somewhat anterior to mouth; internarial space about 1 time the nostril width; no nasoral grooves; eyes dorsolateral on head, narrow subocular ridges present below eyes; mouth angular or semiangular, moderately long, with lower symphysis well behind upper so that upper teeth are exposed in ventral view; labial furrows present along both upper and lower jaws, these very short and ending well behind level of upper symphysis of mouth; branchial region greatly enlarged, distance from spiracles to fifth gill slits 3/4 of head length; gill slits lateral on head. Two equal-sized dorsal fins present, origin of first about one-third of its base length in front of the pelvic origins; origin of second dorsal about over the anal origin; pectoral fins small, their width much less than mouth width; inner margins of pelvic fins not fused over claspers in adult males; claspers moderately long, fairly thick and distally pointed, extending well behind the pelvic fin tips; anal fin moderately large, but not greatly elongated, about as large as pelvic and dorsal fins; base length subequal to second dorsal base; origin of anal well behind pelvic bases, and its insertion separated from lower caudal origin by a broad space over half the anal base; caudal fin moderately elongated, slightly less than a fourth of total length in adults. No crest of denticles on the dorsal caudal margin; supraorbital crests absent from cranium. Colour light to dark brown, without a conspicuous colour pattern.
Remarks:
Specimens of Cephalurus from Panama, Peru and Chile differ from the type species, C. cephalus, in a number of characters and may represent one or more new species (see also Kato, Springer and Wagner, 1967, and Springer, 1979).