Four hundred papers published in refereed papers during the years 1935-1985 were researched for information on the biology of trypanorhynchs, and a publishable host-parasite list was compiled for this period as a complement to the only previous monograph (published forty-five years ago) on all known members of the order Trypanorhyncha (Platyhelminthes: Cestoda). The theoretical information gained from this initial exercise was then used in carrying out original research on trypanorhynchs found in over 1,000 elasmobranch and teleost fish. This led to a choice of three research topics for more detailed investigations: (i) taxonomic studies on four little-known species and the application of this information to fisheries biology, (ii) life-cycle studies on Grillotia erinaceus (van Beneden, 1858) and (iii) the use of Grillotia smaris-gore (Wagener, 1854) Dollfus, 1946 as a biological tag for commercially important teleosts. A pre-requisite of this last problem was the need to review critically all information on the use of parasites as population indicators. Thus a further 100 papers published in primary journals were researched.
The work concludes with a discussion of the above and also brief comments on the need for further research on tapeworms of the order Trypanorhyncha as an aid to our understanding of other basic contemporary problems in parasitology, relating to host-specificity, ecology and phylogeny
