NORTH AMERICAN SPECIES OF THE GENUS AT AX 217 



MEASUREMENTS: 



Male Female 



Length of body 0.501 mm. 0.752 mm. 



Length of leg 1 0.643 mm. 1.112 mm. 



Length of leg II 0.852 mm. 1.607 mm. 



Length of leg III 0.627 mm. 0.959 mm. 



Length of leg IV 0.867 mm. 1.571 mm. 



Length of palpus 0.214 mm. 0.337 mm. 



Of this species, 13 specimens were obtained at L. St. Clair, 

 Aug. 17, 1893, from Anodonta ovata and Oct. 10, 1893, 22 

 specimens were collected at Lansing, Mich., from mussels 

 taken from Cedar River, but unfortunately the record of species 

 of Unionidse has been lost. It was found in considerable 

 abundance at Round Lake, Charlevoix, Mich., in Anodonta 

 sxibcylindracea, A. footiana, A. edentula and TInio luteolus', 

 at "26" and Twin Lakes, in A. edentula, A. footiana and A. 

 fragilis, in limited numbers in the former but more abundantly 

 in the latter lake; and at Intermediate Lake, in Mar 'garitana ru- 

 gosa, Anodonta suhcylindracea, A. footiana, A. edentula and 

 A. fragilis, but in none common. At Beaver Island, Lake 

 Michigan, it was collected rather commonly in Anodonta 

 footiana and A. marry atana taken from a lake towards the 

 south end of the island. At Grand Rapids, Mich. , during the 

 summer of 1895, A. intermedins was found only in Marga- 

 ritana rugosa from two localities on Grand River and only in 

 limited numbers, while during the past summer the same was 

 found to hold true. A few specimens were secured Aug. 17th 

 to 20th, 1898, at White Lake, Muskegon County, Mich., from 

 Anodonta footiana and A. subcylindracea. 



In Nebraska it is a very abundant form, and on one occasion 

 a very large Anodonta plana was fouud to contain 406 speci- 

 mens. It has been collected in ponds at Lincoln, in Weeping 

 Water Creek at Weeping Water and in the Blue River at 

 Milford, from TJnio subrostratus (once), U. James i 'an us (once), 

 Margaritana complanata (occasionally), Anodonta plana, A. 

 decora and A. grandis. The females are almost uniformly in 

 excess, averaging three to each male; of 1178 specimens from 

 the vicinity of Lincoln for example, 275 were males and 893, 



