228 robert h. wolcott: 



measurements: 



Male Female 



Length of body 1.136 mm. 1.419 mm. 



Length of leg 1 1.188 mm. 1.035 mm. 



Length of leg II 1.515 mm. 1.285 mm. 



Length of leg III 1.647 mm. 1.438 mm. 



Length of leg IV 1.958 mm. 1.739 mm. 



This species was the most abundant of all at Lake St. Clair, 

 228 specimens being secured from a number of species of 

 Unionidse, but no definite statement of the exact species in 

 which it was taken can be given, except that among them were 

 IT. alatus, U. ventricosus and IT. luteolus. 



Specimens were secured at Charlevoix, Mich., and vicinity, 

 as follows: in Round Lake, from Anod. subcylindracea, A. foot- 

 iana and IT. luteolus; in u 26 " and Twin Lakes from the same 

 Anodontas and A. edentula and A. frag ills', in South Lake, 

 Beaver Island, Lake Michigan, from IT. luteolus. Nowhere 

 else has this species been found in Anodontas, and I should be 

 tempted to believe that those collected had migrated from ITnio 

 luteolus while the mussels were kept in pails of water a day or 

 two before being examined, were it not that at Twin Lake only 

 Anodontas were collected. The species was rare at all of those 

 localities. 



At Grand Rapids, Mich., A. fossidatus has been found very 

 generally distributed, — in ITnio luteolus at Reed's Lake; in IT. 

 rubiginosus, IT.plicatus, IT. undulatus, IT. j/astalatus, U. Novi- 

 eboraci, IT. occidens, IT. ventricosus, U. ligamentinus, IT. spat- 

 ulatus, IT. rectus, V. coccineus, IT. verrucosus (especially 

 abundant), IT. alatu*, IT. Schoolcrafti, from different localities 

 in Grand River; and in IT. occidens from Rogue River, Kent 

 County. 



The species has also been taken at Lansing, Mich., but from 

 what host is uncertain. At White Lake, Muskegon County, it 

 was found the past summer in IT. luteolus, and at Black Lake, 

 Holland, Mich., it has been collected from that species and 

 from ITnio occidens. 



At Oshkosh, Wis., it has been found in Unio gracilis and 

 IT. luteolus. 



