MUSSEL FAUNA OF MAUMEE KIVER. 



17 



contents are given in detail under the general heading at the close of 

 this report. (See p. 57.) 



When examined in June these mussels were strikingly barren. 

 The only gravid individual noted was an example of Lampsilis 

 ventrieosus with the shell of a marked female contour very much 

 inflated, and this was partly barren, the gills appearing shrunken. 

 Subsequent investigations showed that the sterility of this bed was 

 due partly to the season. As we went downstream and the season 

 advanced we noticed gills of various species beginning to take on a 

 dusky tinge at the margin and filling up with fertilized eggs and 

 glochidia. Moreover, on a visit to this mussel bed on September 21, 

 of 28 examples of L. ligamentinus procured 8 were gxavid. The other 

 species procured in September were: Quadrula tuherculata^ 1; Q. 

 rubiginosa^ 1; Q. undulata^ 3; Symphynota complanata^ 1; Lampsilis 

 rectus^ 3; L. luteolus^ 2; none gravid. The percentage of breeding 

 mussels was hardly as great as one might expect under favorable 

 conditions. No small shells were found, the smallest being of 

 medium size and apparently several years old. The conditions on 

 the whole seem to indicate that this mussel bed is dying out. It 

 would have been possible to secure a number, perhaps a half ton, of 

 good shells here without disturbing the mussels. 



The riffles were incidentally visited in November, and although 

 the water was quite cold the protozoa were still abundant on craw- 

 fishes and dead leaves in the water, and the conditions bore con- 

 siderable resemblance to those observed earlier in the year.^ 



None of the mussels was badly parasitized.^ Atax ypsilophorus^ 

 Aspidogaster conchicola^ and Cotylaspis insignis were rather com- 

 mon, but not abundant. The marginal cyst distomid was rather 

 frequent, and it was here we obtained material with which we were 

 able to associate this organism with pearl formation. It was most 

 common in Lampsilis Ugamenti?ms, 



From the riffles down to the mouth of the river mussels appeared to 

 be quite scarce. 



On June 26, 1909, as opportunity permitted, this place was revisited. It was during 

 a long period of high water. The river, though turbid, was not filthy and appeared 

 1 reasonably clean. At the riffles it was racing at a rapid rate and the current could 

 I hardly be stemmed when about breast-high, but would sweep one off his feet. No Pro- 

 1 tozoa were seen, and only a few yoimg crawfishes, which were very active and alert. 

 I A few gray-back minnows were swimming about on the surface, and schools of small 

 I minnows darted from sbore. By wading about a great deal only two live mussels (L. 

 ligamentinus) were found, though there were a number of dead shells. There were no 

 evidences of unhealthy conditions or overcrowding ; on the contrary, the conditions 

 seemed to be those of an ideal mussel stream. This visit served to emphasize the fact 

 that during periods of high water sewage is comparatively innocuous and that while the 

 water of the river has great variation the river population is fairly constant ; in 

 periods of low water the stream is overpopulated and, to use a chemical phrase, the in- 

 habitants are almost' precipitated out. 



^ The parasites are more fully discussed and described at the end of the report. 



