MUSSEL FAUNA OF MAUMEE RIVER. 53 



145 millimeters long and weighed 4G7 gi'ams. The nacre of all the 

 shells was white. 



L. ligamenthms, the miicket, while not the very best of button 

 shells, is not greatly inferior to the best, and on account of its com- 

 monness and favorable shape and size is the most common species 

 in commercial use. In the upper Mississippi it occasionally has to 

 be discarded on account of its pink nacre, but this feature is wholly 

 absent from Maumee shells. Perhaps 90 per cent of the shells of the 

 Maumee Basin that possess commercial value are L. ligameiitinus. 



This species is rather free from parasites. A few Atax frequently 

 occur, but Gotylasjns^ Aspidogaster, and the other parasites found so 

 frequently in the thin-shell mussels, are usually rare or absent here. 

 Encysted distomids are fairly common, though hardly so common 

 as in L. ventricosus. They are usually found about the edge of the 

 mantle, though they may also be distributed throughout the body. 

 The common form, designated in this report as the marginal-cyst 

 distomid, is of especial interest in this species, as it is occasionally 

 the cause of the formation of pearls. 



This species was not usually found gravid until late in the season. 

 At the beginning of the Maumee investigation, in June, only a few 

 examples were gravid, but the greater number were barren. As we 

 proceeded down the river, it was noticed that in the Auglaize River, 

 August 8, the gills had begun to fill with glochidia and had a faint 

 blackish edge. On a visit to the riffles of the St. Marys on September 

 27 a large number of the mussels were found to be gravid. 



Lampsilis ligamentinus is one of the most easily propagated of 

 fresh-water mussels, and where it produces a heavy shell and white 

 nacre, as it does in the Maumee, is one of the most valuable species 

 for propagation. 



Although well-marked specimens of L. ligcmientinus are easily 

 distinguished from the following species, L. luteolus^ one frequently 

 finds shells which are difficult to identify, apparently standing some- 

 where between the two. 



30. LampsiUs liiteolus (Lamarck). Fat mucket. Lampsilis liite- 

 olus was found in about the same situations as L. ligamentinus but 

 not in such abundance. Most of the examples seen were collected 

 and the number of shells in our Maumee collection is 134. None of 

 our specimens are of the variety rosaceous^ which is a form belonging 

 to the St. Lawrence drainage. 



Unlike L. ligamentinus^ this species is usually abundant in lakes, 

 as well as being an inhabitant of rivers. It is indeed one of our 

 characteristic lake shells. We obtained a number from Put-in Bay 

 Island, Lake Erie, but they were rather small, as is usual with lake- 

 dwelling individuals. The examples found in the St. Joseph Eiver 

 and the feeder canal were remarkably large and fine. This species 



