384 



ALMOST COMPLETE EXTINCTION OF AN ABUNDANT AND 

 VARIED MUSSEL FAUNA SINCE 1913-1915 



If we add to the list of exterminated small bottom animals the 

 most of the mussels found by Danglade (1914) in Peoria Lake in 1911 

 and 1912, and now apparently all gone but an inconsequential number 

 of the hardier species in the lower lake, this addition raises the total 

 of missing bottom species from more than twenty to more than sixty 

 kinds. Danglade listed in all, from the three lakes, a total of forty- 

 one species, of which twenty came from Chillicothe and thirty from 

 the middle lake. The number of kinds taken in the lower lake was 

 not stated. The location of the most important commercial mussel 

 beds as described by Danglade as they existed in 1911-1912, included 

 beds above and below Rome : a mile above' Spring Bay and in Spring 

 Bay Narrows ; below Mossville ; and between Al Fresco Park and 

 Peoria Narrows. The continued existence in good condition of the 

 Mossville and Al Fresco Park beds, and of a vast bed of bluepoints. 

 (Ouadnda plicata) more than two miles long in the lower lake, extend- 

 ing from the center of the channel eastward, was verified by sketch 

 maps furnished us as late as November 1915 by Havana pearl-hunters 

 who spent the summer and fall of 1915 in Peoria Lake. 



In the summer of 1930 and of 1922 we took with the Petersen 

 dredge a single specimen each in the lower lake of two species, but no 

 trace of live mussels of any kind in the waters above Peoria Narrows. 

 We also, in July 1920, went carefully over a small boatload of mussel 

 shells taken with a dip-net the same day by a Peoria musseler who we 

 thought must have a market for dead shells to justify the otherwise 

 unproductive work that he was doing. The number of shells we 

 found alive was extremely few and all belonged to one or the other of 

 two species, the bluepoint, Ouadrnla plicata; or the warty-back, Quad- 

 rtiki pHsltilosa. It is significant that both of these species were taken 

 by us farther north in the polluted upper Illinois River in the summer 

 of 1912 than any other mussels with the exception of one species 

 {Sympltyiiota cuinplanata) ; the first having been taken at Starved 

 Rock in company with 5". complanata; and the second at Spring Valley. 



The list of Peoria Lake mussels as of 1911-1913 that follows is 

 as presented by Danglade (191-i), except for the starring of the two 

 unusually tolerant species of Quadrula above noted, and of theappar- 

 ently hardy dwarf species of Anodonta which wc took with the Peter- 



