592 FOSSIL UNIOS FKOM TORONTO SIMPSON. 



into other regions, 1 know of but ;i single species belonging elsewhere 

 tliiit has been found within tliis basin, a case that I shall refer to later.* 



The streams of T«'xas are almost wholly peopled with these and 

 closely related forms, which, in some cases, exteiul well into Eastern 

 Mexico, and even Central and Nortliern Houth xVmerica. To tlie north- 

 w^ard and eastward a number of characteristic Mississippi Uuiones have 

 extended into the Ked River of the North, the Saskatchewan, the 

 Mackenzie, to the Hudson Bay Territory, Michigan, and Canada. It is 

 probable that one of these si)ecies is even found in the Columbia Kiver, 

 Unio luteolu-s, where it is known by the name of U. oregonensis. It will 

 be therefore seen that the Naiades of this region are vigorous and ag- 

 gressive. 



The waters that drain into the Atlantic are inhabited l)y a totally 

 different set of Uniones, which, as a rule, are moderate in size, of rather 

 frail structure, and not remarkable for color or sculpture. The Appa- 

 lachian chain acts as an almost total barrier to the mingling of the 

 forms of the two areas, and, so far as is known, only a. very few of these 

 eastern species extend westward to the headwaters of the St. Lawrence. 



Tlie following is a list of shells sent by Mr. Coleman : 



JJitio phaseohts Ilild. Six valves. An abuiulant, widely distributed 

 species, whose recorded northern limits are western New York, Che- 

 boygan County, Michigan, near the MackinaAV Straits, and St. Peters, 

 Minn. 



[Jnio occulens Lea? Part of a right valve. It is foniul living as far 

 north as Ottawa, Canada. 



U71I0 puatuJosHH Lea. Six valves in bad condition, which 1 believe to 

 be typical 2)u,stulosm. Not reported outside the Mississip])i area. It 

 extends north to St. Peters, Minn., and southern Wisconsin. 



Uiilo pustuloHUs var. SchoolGrafti Lea. Four valves and the posterior 

 part of a pair. It o(;cnj's north to Grainl liapids, Mich., and Lake Erie. 



(Inio K)i(lul<(ti(.s liar. Part of a left valve in bad condition, but un- 

 doubtedly this species. Mississippi area into Texas, north to Ottawa, 

 and Ued River of the North. 



rnio rectus Lam. Ivight valve of a young specinien. Widely dis- 

 tributed, extending to Ottawa and the Red River of the North. 



* No. 85981 of the Isaac Lea colkut imi, now in the National Musiuiii, was seut to 

 Mr. Lea from the pouds of the Waljash by Dr. Lewis, aud labeled by the latter 

 "Unio subrostraliis Say." The former changed it to nasuliis. No. 85938, same col- 

 lection, Foote's I'ond, Gibson ('(tunty, Indiana, -wa« labeled I', nasutns by Lea. I 

 have carefully examined these shells and unhesitatingly i)rououuce them to be U. 

 stibroniratus, a forui closely resembling U. nasutns at times, but always nuire inllated 

 and differently shaped in the ventral region. There are authentic shells of r.nasuiHa 

 from Ohio in Dr. Lea's collection, but they are all from streams that fall into Lake 

 Erie. One Unio in the Museum collection (No. 2()060), from J. A. Laphani, is labeled 

 U. radiatus, Pine, northeast boundary of Wisconsin. Pine County is in Minnesota, 

 near Lake Superior, and is drained by the St. Croix River, a tributary of the Missis- 

 sippi. I am inclined to refer this specimen to the very nearly related Unio htteolus, a 

 common Mississippi Basin species. 



