General Discussion

The major features of the life history of Bucephalus longicornutus agree with those described for fresh-water bucephalids by Woodhead (1929, 1930), and Kniskern, 1952) and it would now seem probable that the type of life history displayed by these species is typical of all members of the family, whether freshwater or marine.

A consideration of the life history of B. longicornutus shows there is still no way of determining the generic status of a cercaria other than by infection experiments although an alternative means has been suggested (p. 22). The latter means is hypothetical and yet to be tested.

Generic identity can be assigned to the metacercaria but its specific identity must be obtained from experimental infections.

It should be stressed again that future investigators must give more accurate descriptions of sporocysts; cercariae and metacercariae than have previously been given by many authors. Because of the close morphological similarity of bucephalid cercariae, information on flame cell formulae, behaviour and all essential details of spination and granulation will be necessary for separation of species. The variability of adult B. varicus and B. longicornutus noted on p. 36 may also apply to other species and genera of the family, and systematists are urged to avoid the tenuous criteria that have, hitherto, been used to differentiate between species.