PEARLY FRESH-WATER MUSSELS 77 



SESSIONAL PAPER No. 38a 



than ever before. Such encouraging reports have come in from Lake Pepin, Wis- 

 consin; White and Black rivers, Arkansas, and from Fairport, in the vicinity of 

 the station. 



THE SOJOURN AT THE STATION. 



My sojourn at the station, July 25, Au^st 3, was both highly profitable and very 

 pleasant. Laboratory accommodation and facilities were freely offered. Valuable 

 instruction, demonstrations and advice were gladly given by the Director and his 

 staff. By assisting in the examination of gills for natural infection, and in carrying 

 out artificial infection under the supervision of an experienced man, I was enabled 

 t<' get a working knowledge of the operations, which would have been quite impossible 

 +0 obtain otherwise. 



The kindness with which I was received, the consideration shown for my wants and 

 comfort, and the pleasure taken in facilitating the object of my visit were beyond my 

 highest anticipations. In this connection I wish to particularly mention Mr. A. Shira, 

 the Director; Mr. Canfield, Superintendent of Fish Culture; Prof. Clark and Dr. 

 Howard, Scientific Assistants; Mr. Gorham, Foreman, and Mr. Southall, Shell Expert. 

 The Station has also kindly sent me a set of classified shells, thereby facilitating 

 classification here. 



ORIGIN OF OUR LARGER MUSSEL FAUNA. 



The identity of the mussel fauna of certain Canadian areas with that of the 

 Mississippi waters at once suggests a probable common origin. Our forms no doubt 

 migrnted northward on the retreat of the ice cap which is believed to have covered 

 northern North America during the great ice age. As this ice field retreated toward 

 the North West, numerous lakes were formed, now represented by our modern Great 

 Lakes, and these probably all except lake Ontario drained into the Mississippi 

 ;;ystem. Several of the old drainage courses have been discovered, among them being 

 the ancient Lake Erie outlet, by way of the Wabash into the Mississippi river, and 

 the glacial lake Chicago along the Chicago river. Even lake Superior appears to 

 have had a watercourse into the Mississippi by way of the St. Croix river.^ Numerous 

 species of mussels no doubt found their way up these waterways into the ancient 

 lakes, and ultimately populated the rivers now flowing into them. 



THE GRAND RIVER. 



As far as I have been able to ascertain, the Grand river contains more mussels of 

 commercial value than any other Ontario waters. This river rises in the township of 

 Melancthon, Dufferin county, within a distance of almost twenty-five miles fron? 

 Georgian bay. Its source, at an elevation of approximately 1.700 feet above sea-level 

 may be said to mark the highlands of the southwestern Ontario plateau. From its 

 source to its outlet into lake Erie, at Port Maitland, by the river, the distance is 173 

 miles and the drainage area is approximately 2,500 square miles. The drainage basin 

 is wide at its headwater area, and narrow in the lower flat country, where most of the 

 rivers flow directly into the lake. 



The river may be topographically divided into two parts — upper and lower. The 

 upper part extends well into Waterloo County and includes the Conestogo tributary. 

 Here, on the flat headwater table lands, the declivity is small; then for a distance 

 becomes quite steep. At Elora, for example, there is a single drop of over 40 feet where 

 the river enters a limestone gorge. The fall of the lower river is gradual and uniform, 

 and generally becomes flat towards the lake. The following table will show the approxi- 

 mate fall of the whole river. 



iPop. Sc. Monthly XL,VI No. ?, p. 217. U.S. Geol. Survey Monographs, XXXVIIa. 



