Some observations on the life history of Strophitus edentulus

Abstract

Text is the Introduction to this thesis: Strophitus edentulus is a fresh water mussel which has been said to go through its metamorphosis both as a parasite on fish (Howard 1914) and without parasitism (Lefevre and Curtis 1912). This condition in Strophitus is rendered more interesting by the fact that there is but one other exception to the parasitic habit among the fresh water mussels. This exception, Anodonta imbecillis (Say), is one of the hermaphroditic species and is not closely related to Strophitus. Since these two species are widely separated in structure, and since the same changes are occurring in each form, it is possible that we have here a case of convergent evolution, the investigation of which may throw some light on the nature of this most interesting adaptation of the fresh water mussels. In the following paper I have presented a review of the observations and experiments from which the above conclusions were drawn, together with some additional data which I have collected myself and a discussion of certain uncompleted and unpublished work which was placed in my hands.