. The Canadian field-naturalist. vm>M,iimimi'mmjnf»W^"-. & tml llltHHtptllllttitttttltillpil Figure \. Moxostoma duquesnei collected from the Nith River: upper specimen, NMC 78-1; middle, WLU5233; lower, WLU5594. a zone of rapids followed by a deep pool. The rapids had a boulder bottom with a depth up to 1 m. At low water levels, the pool was effectively divided by a gravel bar into two smaller pools. At the time of capture the depth of the pool was about 75 cm. The sides were gravel and the bottom was covered in fine silt. Both specimens were collected from the pool. One specimen
. The Canadian field-naturalist. vm>M,iimimi'mmjnf»W^"-. & tml llltHHtptllllttitttttltillpil Figure \. Moxostoma duquesnei collected from the Nith River: upper specimen, NMC 78-1; middle, WLU5233; lower, WLU5594. a zone of rapids followed by a deep pool. The rapids had a boulder bottom with a depth up to 1 m. At low water levels, the pool was effectively divided by a gravel bar into two smaller pools. At the time of capture the depth of the pool was about 75 cm. The sides were gravel and the bottom was covered in fine silt. Both specimens were collected from the pool. One specimen is deposited in the Wilfrid Laurier Uni- versity Museum as WLU5233, and the other at the National Museum of Natural Sciences, Ottawa as NMC78-1. Moxostoma erythrurum. Golden Redhorse, was collected with M. duquesnei at the first locality and M. macrolepidotum, Shorthead Redhorse, was col- lected at the second locality. The earlier and recently collected specimens of M. duquesnei agree in morphology and coloration with the species from elsewhere in the Lake Erie basin (tributaries in the United States) and from through- out most of the wide range of the species in the United States, from the southern parts of the lakes Ontario, Huron, and Michigan basins and southward. The species in the Nith River system that most closely resembles M. duquesnei is M. erythrurum. Many workers encounter difficulty in distinguishing them. The following meristic data (taken by methods of Hubbs and Lagler 1958) are from specimens from the Lake Erie basin of Canada and the United States unless otherwise stated (Jenkins 1970 and subsequent study). The best character for separation of these two species is the lateral-line scale count: M. duquesnei ranges 45^8, x = , N = 28: M. erythrurum 39^4, X =, N = 46. Slightly overlapping counts may be expected from additional specimens. Other meristic differences are the following: body circumferential scales (axis just anterior to dorsal fin), M. duques
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