Haplochitonidæ.

Body naked or scaly. Margin of the upper jaw formed by the intermaxillary; opercular apparatus complete. Barbels, none. Gill-opening wide; pseudobranchiæ well developed. Air-bladder simple. Adipose fin present. Ovaries laminated; the eggs fall into the cavity of the abdomen, there being no oviduct. Pyloric appendages, none.

Fresh-water fish from the temperate parts of South America and South Australia, representing the Salmonoids of the northern hemisphere.

Prototroctes marama. Rivers of Southern Australia. "Herring." "Grayling."