_Protopterus annectens_ is the “Lepidosiren” which is commonly found in Zoological collections. It is usually imported from the west coast of Africa, where it abounds in many localities; but it is spread over the whole of tropical Africa, and forms in many districts of the central parts a regular article of food. [Illustration: Fig. 138.--Protopterus annectens. _g_, Branchial filaments; _v_, vent.] During the dry season, specimens living in shallow waters which periodically dry up, form a cavity in the mud, the inside of which they line with a protecting capsule of mucus, and from which they emerge again when the rains refill the pools inhabited by them. Whilst they remain in this torpid state of existence, the clay-balls containing them are frequently dug out, and if the capsules are not broken, the fishes imbedded in them can be transported to Europe, and released by being immersed in slightly tepid water. _Protopterus_ is exclusively carnivorous, feeding on water-insects, frogs, and fishes, and attains a length of six feet. [Owen, “Trans. Linn. Soc.” 1841, xviii.] CERATODUS.--Body elongate, compressed, with one continuous vertical fin. Limbs paddle-shaped, with broad, rayed fringe. Vomerine teeth incisor-like; molars with flat, undulated surface, and lateral prongs. No external branchial appendages. Conus arteriosus with transverse series of valves. Ovaries transversely lamellated.[39] [Illustration: Fig. 139.--_Ceratodus miolepis._] Two species, _C. forsteri_ and _C. miolepis_, are known from fresh waters of Queensland. The specimens hitherto obtained have come from the Burnett, Dawson, and Mary rivers, some from the fresh waters of the upper parts, others from the lower brackish portions. The fish is said to attain to a weight of twenty pounds and to a length of 6 feet. Locally, the settlers call it “Flat-head,” “Burnett- or Dawson-Salmon,” and the aborigines “Barramunda,” a name which they appear to apply also to other large-scaled freshwater fishes, as the Osteoglossum leichardti. In the stomach there is generally found an enormous quantity of the leaves of plants growing on the banks of rivers, evidently eaten after they had fallen into the water and when in a decomposing condition. The flesh of the fish is salmon-coloured, and much esteemed as food.