70 



MUSSEL FAUNA OF MAUMEE EIVEE. 



extent as to V\^holly obliterate it and render the mussel incapable of 

 reproduction. In those mussels (Lampsilis gracilis^ L. luteolus^ etc.) 

 in which there is a marked difference in the form of the shell of the 

 two sexes, BucephaluSj by arresting sexual development at various 

 periods of the mussel's life, stops also the development of the peculiar 

 form of shell characteristic of the sex. Shells are thus left at vari- 

 ous intermediate stages of sexual development, though they may 

 attain full size, and this has doubtless led to considerable perplexity 

 in identifying them, or even to the descriptions of new species. It 

 may also be partly responsible for the large amount of synonymy 

 found in the Lampsilis ventricosus group. 



It can be readily inferred that the introduction of Buceplvaliis- 

 infected mussels into places where breeding or breeding experiments 

 are being carried on would be likely to produce disastrous results. In 

 collecting mussels for propagating purposes, therefore, shells of in- 

 different contour as regards sexual peculiarities should be vieweti 

 with suspicion. In addition, examples should be dissected to detect 

 signs of the presence or absence of the trematode. 



The mature form of Bucephalus polymorphus is Gasterostomum 

 -fhTYhbriatum von Siebold, which is a parasite of the pike (Esow) and 

 perch (Perca), and an intermediate host (eaten by the final host) is 

 some species of minnow. (Leuciscus is one of the known hosts.) In 

 ponds devoted to the breeding of mussels the ravages of Bucephalus 

 might be held in check by avoiding the peculiar combination of mus- 

 sel, minnow, and pike or perch, provided of course these were not the 

 particular species of fishes required to carry the glochidia. 



7. Ascaris-like, worms Avere occasionally found in the alimentary 

 canals of mussels, and are probably to be regarded as parasites. 



8. Leeches were found quite frequently on the inside of the shells 

 of Anodonta, in all probability genuine parasites. They appear to 

 be quite fond of the mucus of mussels, as is shown by the following 

 observation: On the inside of a number of valves cleaned by musk- 

 rats and left on the bottom in Lake Maxinkuckee, the leeches were 

 found to have accumulated in considerable numbers. Leeches also 

 frequentl}^ attack other species of mollusks, as Planorhis, in large 

 numbers. It could not be ascertained whether they injured the mus- 

 sels to any- marked extent or not. 



9. Atax ypsilophorus was a common parasite of mussels through- 

 out the length of the river, and was particularly common on Ano- 

 donta in the reservoir of the feeder canal. An example of Atax^ 

 probably this species, found in a mussel at the riffles of the St. Marys 

 River, was so heavily burdened with a growth of Vorticella on its 

 body that it could hardly move about. We came across several other 

 specimens similarly affected. 



