ON SOME FOSSIL UNIOS AND OTHER FRESH-WATER SHELLS 

 FROM THE DRIFT AT TORONTO, CANADA: WITH A REVIEW OF 

 THE DISTRIBUTION OF THE UNIONID^E OF NORTHEASTERN 

 NORTH AMERICA. 



HV 



Chas. T. Simpson, 



Aid, Deparlntoit of Mollusks. 



The United States National JMuseuni has recently received from 

 Mr. A. P. Coleman, of the Hcliool of Practical Science of Toronto, a 

 number of fossil llnios and other fresh- water shells from the drift of 

 that city, the foiiner of whicli are highly important in their bearings 

 on the <listribution of (■ertain s[)e<M<'S of that genus. Tliey were ob- 

 tained from a bed of sand between two glacial beds in a railway cut 

 on the Belt Line, north «»f Windiester street, 20 to 25 feet above the 

 River Don. 



Eight species and one variety of Unios and six species of other fresh- 

 water shells were sent, all of whi(;h are living at the present day. All 

 the Unios are characteristic forms of the Mississippi V^alley, but of 

 these only three species have ever been reportcMl from Canada. 



The material was received in rather bad condition; in the case of 

 the Unios the valves were all more or less broken and somewhat 

 crumbled, yet T have been able- to identify with certainty most of the 

 specimens. 



It may be well before giving a list of these specimens, and stating 

 the range which they at present occupy, to brieliy <»utliiie the distri- 

 bution of the (nionidw of Eastern North America. 1 shall not go into 

 details legarding this matter, which 1 have treated at length in a 

 paper recently ])u])lished in the American Naturalist.* 



Sufli(;e it to say that at the present time a common assemblage of 

 the Naiades inhabits the entire Mississipi>i I)ri#nage Area, to tin*, al- 

 most absolntc exclusion of all other i'ornis. Within this rt'gion is 

 found the most jnagniticent d<'vel(>i»m('nt of the I'liionida* of any part 

 of the world. It is an ancient fauna, having descended in a no doubt 

 unbroken line, and through forms which have in some cases scarcely 

 changed, from the Cretaceous period. Tlu^ specdes an«l individuals are 

 exceedingly numerous; they are often very large and ponderous, orna- 

 mented with beautiful and odd patterns of color and sculpture. Unione 

 life seems to have run riot here, and theie is only one other area in the 

 world at all comitarableto it in thisrespect^ — that of China — which has 

 no doubt received a part of its stock fiom the same source as the ter- 

 ritory in (luestion. 



While man}^ sjxM^ies actually fonnd within this area, and others be- 

 longing with groups having their metropolis here, have spread far out 



*On the Relatioushipu aud Distributiou of the North American Unionidw, with 

 notes OQ the West Coast Species. American Naturalist, Vol. xxvii, No. 316, p. 353. 

 FroceedingA National Museum, Vol. XVI— JTo. 052, 



591 



