322 Io and its Habits. [June, 
24,1870. If there were any persons aware of the occurrence of 
Io in streams other than the Holston River prior to that date, 
they probably had reasons for not publishing the fact. Since the 
date quoted, however, it has been ascertained that the distribution 
of Io extends to several streams in East Tennessee, rendering it 
quite probable that future explorations may lead to its detection 
in the southern part of Eastern Kentucky, and in the northern 
part of Western North Carolina. At the present time Io is known 
to occur in the following streams: North Fork of the Holston in 
Western Virginia; in the Holston River in East Tennessee; in 
the Tennessee River as far south as Bridgeport, Alabama; in the 
Nolachucky and French Broad rivers in Jefferson County, Tenn. 3 
in the Clinch River at Black’s Ford, Anderson County, Tenn., 
and at Williams’ Ford in Roane County, Tenn.; and in Powell’s 
River at Kraushorn’s Ferry, near the State of Kentucky. 
Observers who have made any records of the habits of To agree 
in stating that the shells are found only in swift water, though 
there appear to be discrepancies as to the abundance of speci- 
mens, which may indicate that some localities are more favorable 
for them than others. It must be inferred that Io, living in 
streams the currents of which are very rapid, is specially organized, 
and adapted to the situations in which it is found. Such, indeed, 
seems really to be the case ; for a lady who collected specimens 
in some of the rivers of Tennessee wrote of them as follows: 
** The muscular power of Jo is astonishing. I frequently find one 
adhering to a rock half as large as"my head, and when I take up 
the shell it brings the rock with it, and requires much force to 
` separate it.” 
It is somewhat strange that shells of so much beauty as Aom 
of the species.of Io display are scarcely known to the inhabitants 
dwelling in the neighborhood of the streams in which they occu; 
et it seems, from records made of the contents of ancient buri: 
places, that they were known to the people who inhabited the 
country prior to the advent of European races. Mr. Lea, writing 
upon this subject,2 makes the following suggestive remark, which © 
conveys a great deal in a few words: “ Professor Troost informs 
me they [Ios] are rare in the river [Holston]; that they had 
been observed in the graves of the aborigines; and as it was 8°” 
erally believed that these were ‘conch shells,’ consequently co 
ing from the sea, it was urged that the inhabitants who poss? 
1 American Journal of Conchology, vi. 223. 
2 Observations, ete., i, 224. 
