the high incidence of Davisia n.gen. in the urinary bladder of Diplocrepis puniceus. The most widespread myxosporidian was the cosmopolitan Myxidium incurvatum Thélohan, this species being recorded from 22 fishes belonging to four species. A new species each of Leptotheca and Sphaeromyxa, these having two hosts, and a single sporulating trophozoite of an undetermined species of Zschokkella, were also discovered.

Haematozoa were found in 63 (13.8 per cent.) of the fishes, six of the 10 species studied acting as hosts. Haemogregarina bigemina Laveran and Mesnil accounted for the bulk of these records, infecting 56 fishes of five species. Eight of these fishes were also positive for Trypanosoma tripterygium Laird, one of the three species concerned, Ericentrus rubrus, being a new host for this flagellate. A single example of Tripterygion medium was parasitized by the trypanosome only. Six of the 11 examples of Acanthoclinus quadridactylus collected at Tolaga Bay were lightly infected with a new species of haemogregarine, possibly referable to Hepatozoon Miller, a genus occurring in reptiles, birds and mammals, but not hitherto known from fishes.

A new species of Myxosoma, found in the subdermal connective tissue of a single example of Tripterygion varium collected at Wellington, was the only histozoic myxosporidian noted during the investigation. There was no outward sign of the presence of this parasite, which thus could not be conveniently searched for during field trips. Future investigations might reveal the presence of more histozoic sporozoans in the fishes dealt with than did the present studies.

Although fresh rectal contents and stained gut smears were examined throughout the survey, intestinal Protozoa were never found. Previous investigators have not described such protozoans from intertidal zone fishes. Some trematodes were discovered, but these will be dealt with elsewhere.

Double infections with Myxosporidia were never recorded from the same organ of any one particular fish. As regards haematozoans, Trypanosoma was in all but one instance associated with Haemogregarina. In the case of the gill protozoans, Scyphidia was only found in association with Trichodina. Caliperia n.gen., with the exception of a single pure infection from Oliverichtus melobesia, was similarly always associated with Trichodina. Double infections with two species of the latter genus were frequently encountered. All the fishes doubly parasitized by Trypanosoma and Haemogregarina were infested with Trichodina as well, and many of those having two different ciliates on the gills were also infected by a blood parasite or a myxosporidian. One example of Oliverichtus melobesia from Wellington had Haemogregarina in its blood, Myxidium in its gall bladder and Caliperia and one species of Trichodina on its gills. Obvious clinical symptoms of disease were never manifest in any of the fishes studied. Such pathogenic effects as became apparent during dissection and microscopical examination are detailed separately for each species in the following systematic account.