loo THE POPULAR SCIENCE MONTHLY. 



than a year, and instances of the survival of nnios without mois- 

 ture for long periods are not rare. While living in south Florida 

 I discovered a colony of unios in a small drain that ran through 

 the pine woods and which only contained water during the rainy 

 season some three months in the year. Thousands of these 

 mussels were found in the channel among bulrushes, buried ver- 

 tically an inch or so below the surface in nearly dry soil, with 

 the anterior end downward, and the slightly moist, sandy banks 

 in many places were full of them. The colony extended some 

 ten or a dozen yards along this drain ; not a specimea could be 

 found either above or below this space, and the species was not 

 found in the little stream into which it emptied. 



A lot of these unios were taken home and laid in the garden, 

 where they remained more than three months wholly unpro- 

 tected from the hot autumn sunlight during the dry season, and 

 when opened a number of them were found to be alive. Yet 

 ordinarily the want of water causes the UnionidcB to speedily die. 

 The summer of 1886 was one of the least rainfall ever known in 

 the upper Mississippi Valley, and many streams and ponds went 

 dry that had never been known to be so before. At this time I 

 collected in northern Illinois and Iowa, and in every instance 

 where the water had evaporated I found the mussels dying by 

 thousands, though in many cases the mud was too soft to bear 

 the collector. While collecting in the Indian Territory I visited 

 a large pond near McAllister that had just been drained, and, 

 although the water stood everywhere in pools, yet the UnionidcB 

 were apparently all dead and gaping open, and the stench was so 

 horrible that the struggle between duty and comfort was a severe 

 one. For years I have watched the dredging operations in the 

 Potomac at the capital, as the mud was thrown out on the flats, 

 and in every case the mussels were dead before it was firm enough 

 to be trodden on. 



I do not believe in building a theory on too slight a foundation 

 of fact, but I am of the opinion that these unios which have been 

 kept dormant for lengthened periods out of water inhabited 

 streams or ponds that were intermittent. The instance I have 

 given in Florida is a good one, and the mussel Dr. Gray received 

 from Australia is no doubt another. The whole island is noted 

 for heat and long-continued droughts, and with scarcely an excep- 

 tion the streams and lakes go dry during the rainless season. 

 Even the Murray River, the largest stream in the country, and 

 ordinarily navigable for hundreds of miles, sometimes ceases to 

 flow altogether.* 



* Other cases in point are known. In the spring of 1887 I collected several specimens 

 of Anodonta Ferussacciana in lagoons along the banks of the South Platte River near 



