Amongst material forwarded to me by Dr. M. J. Mackerras of the Queensland Institute of Medical Research, were cestodes collected from several specimens of Rattus assimilis (Gould, 1858), from Mt. Glorious, South Queensland and Innisfail, North Queensland. These cestodes have been identified as (i) Hymenolepis diminuta Rudolphi, 1819; (ii) Raillietina (Raillietina) celebensis (Janicki, 1902) (see Baer and Sandars, 1956) ; (iii) Choanotaenia ratticola n.sp ; (iv) Hymenolepis australiensis n.sp. ; (v) one misshapen cysticercus of Taenia taeniaeformis (Batsch, 1786). Of these (i), (ii) and (v) appear to be new host records for Australia while (iii) and (iv) are new species.Whole mounts of all these cestodes were prepared by staining in hydrochloric-alcohol-carmine and some were stained in weak haemalum. They were all mounted in Canada balsam. Scolices were also mounted in berlase medium, some of which were squashed to facilitate the detailed study of the rostellar hooks. Sections were cut at 9 \L and stained in haemalum and eosin. Measurements given were made from mounted specimens.* On study leave from the University of Queensland and the Queensland