The diet of the barn owl in the Nigerian savanna was determined by analysis of 739 prey remains, made up largely of small mammalian species. Small mammals accounted for 92.2% of all remains, with rodents (76.0%), insectivores (12.3%) and chiropterans (3.1%) being the primary prey groups. Unidenti¢ed mammals accounted for 0.8%. Nile rat Arvicanthis niloticus was the favourite prey and accounted for 30.9% of all prey and 26.5% of prey biomass. Food habits varied among the four geo-ecological zones of the Nigerian savanna studied in several respects. The diets in Nguru and Baga were more diversi¢ed than in the other locations. Birds accounted for 4.7%, reptiles 1.6%, amphibians 1.1% and insects 0.4%. As a result of the preponderance of rodents and some granivorous birds in the diet of barn owls, the owls are deemed to be playing an important role in the biological control of these potential agricultural pests.

The similarities between Opecoelus Ozaki, 1925, Coitocaecum Nicoll, 1915, Opegaster Ozaki, 1928 and Paropecoelus Pritchard, 1966 and the difficulty of separating Opecoelus and Opegaster are discussed. It is proposed that Opegaster be reduced to synonymy with Opecoelus and the diagnosis of the latter amended to accommodate both forms. Four new species of Opecoelus are described from marine teleosts in Australian waters. These are Opecoelus woolcockae n. sp. from Acanthopagrus butcheri and A. australis from off South Australia, New South Wales and southern Queensland, O. pomatomi n. sp. from Pomatomus saltatrix off New South Wales, O. crowcrofti n. sp. from Atherinomorus ogilbyi off southern Queensland and O. queenslandicus n. sp. from Apogon fasciatus off southern Queensland. The following new combinations are formed: Opecoelus gonorhynchi (Gavrilyuk, 1979) n. comb., O. elongatus (Yamaguti, 1959) n. comb., O. pentadactylus (Manter, 1940) n. comb., O. apogonichthydis (Yamaguti, 1938) n. comb., O. cameroni (Caballero & Caballero, 1969) n. comb., O. dendrochiri (Yamaguti, 1970) n. comb., O. hawaiiensis (Yamaguti, 1970) n. comb., O. jamunicus (Srivastava, 1968) n. comb., O. longivesiculus (Yamaguti, 1952) n. comb., O. mastacembalii (Harshey, 1937) n. comb., O. mehrii (Harshey, 1937) n. comb., O. synodi (Manter, 1947) n. comb., O. tamori (Yamaguti, 1938) n. comb., O. bothi (Yamaguti, 1970) n. comb., O. caulopsettae (Manter, 1954) n. comb., O. beliyai (Pande, 1937) n. comb., O. brevifistulus (Ozaki, 1928) n. comb., O. cryptocentri (Yamaguti, 1958) n. comb., O. dactylopteri (Yamaguti, 1970) n. comb., O. dermatogenyos (Yamaguti, 1970) n. comb., O. ditrematis (Yamaguti, 1942) n. comb., O. gobii (Yamaguti, 1952) n. comb., O. hippocampi (Shen, 1982) n. comb., O. iniistii (Yamaguti, 1970) n. comb., O. lobulus (Wang, 1977) n. comb., O. macrorchis (Yamaguti, 1938) n. comb., O. parapristipomatis (Yamaguti, 1934) n. comb., O. pritchardae (Overstreet, 1969) n. comb., O. syngnathi (Yamaguti, 1934) n. comb., O. lutiani (Bravo-Hollis & Manter, 1957) n. comb., O. ovatus (Ozaki, 1928) n. comb., O. plotosi (Yamaguti, 1940) n. comb. and O. rectus (Ozaki, 1928) n. comb.; all the new combinations were previously species of Opegaster.

Helicometra Odhner, 1902 is reported from temperate Australian marine teleosts in which it appears to be rare. Of 285 species of fishes from 84 families examined, only 10 species from 9 families were infected. One infection, that in Platycephalus speculator caught from off the coast of Western Australia, is highly distinctive and the name Helicometra sprenti n. sp. is proposed for this species. The other infections were from members of the Antennariidae, Apogonidae, Kyphosidae, Labridae, Paralichthyidae, Pinguipedidae, Scorpaenidae and Sparidae, all from off southern Queensland and New South Wales. There is no evidence that infections are common in any of these hosts, which have little relationship to each other. Measurements and figures are presented for representatives from all the host species. Only minor variation was found in features such as body dimensions and the extent of the vitelline follicles, and it is concluded that the specimens probably represent a single species with a very low host-specificity. We suspect that the general scarcity of the worm is consistent with the presence of only one species, although the possibility that a species-complex is present cannot be ruled out. The specimens are broadly consistent with H. fasciata (Rudolphi, 1819), a species first described from Europe, and they are tentatively identified as this species, although it seems likely that ultimately they will prove to represent a different taxon. Determination of the ultimate identity of this form will require the application of molecular and life-cycle studies of worms from different hosts and localities.