RK-191

The Grove [circled] 7 West Northfield, Ill. Oct 20^th 1856

Dear Sir.

I spent this afternoon in wading in the River Des Plaines (a tributary of the Illinois River) hunting shells for you.

I was unable to find many bivalves con[page torn] the living animals, but managed to find a [page torn] shells about stones and logs, the contents of which had been devoured by that "Conchologists assista[page torn] - the muskrat. For want of better specimens I shall send you some poor ones. Thinking they may be of some use in comparing, observing varieties &c, though not good for cabinet specimens.

This river is a small stream and rather sluggish Enlarging to great size annually at the time of [illegible]. It is now very low.

I found what I suppose to be melania cana iculata in almost incredable quantities. I estimated the average number at about ^over twenty to every square foot of the whole surface [page torn] the river - though there would be large [page torn] in stagnent water (that is behind points where the [page torn] could not come) where the shells lay so thick as to comple[page torn] cover the bottom - all touching each other. The shells all contained the living animal. I observed that in moving about they often followed in each other[page torn] tracks as if 'twere easier to travel so. I observed a specimen about an inch long moved about his own

length in two minutes. So a "snails pace" is 30 inches an hour. I am not at all sure I am correct as to the name of this species. Mr Lapham could not name it, but it looks like an imperfect specimen of M. Canaliculata given me by Dr Kirtland. [page torn] send you a hundred specimens or so.

[page torn] did not find Lynnia ^{Paludina ponderosa} so abundant [page torn] I have sometimes seen it in spring. There were twenty of the melania to one of P. ponderosa. I believe the latter is very abundant in all the tributaries of the Illinois in this region.

Plarorbis trivolvis (I suppose it to be) but you'll know by the specimens) is abundant in this river - it is also very abundant in our prairie sloughs - but I found few specimens to day and none containing the living animal I think.

I found the empty shells of cyclas similis in great abundance, but I think I found no living specimens at all. this species is very abundant in our prairie sloughs.

This summer I found Lymnea jugularis (true) [page torn] abundance in a prairie stre small prairie stream made of spring water. I do not remember to have seen it in the river (into which this stream empties) nor in the prairie sloughs - from Dr Kirtlands observations I had supposed it an inhabitant of stagnant water. - However, upon second thoughts I remember that though the creek in which I observed

it this summer had a rapid currant, it had a muddy bottom - or at least one not strong was full of grass and in places widened out into little lakes where the currant was imperceptable - I doubt ^myself whether this shell could exist in rivers with rapid currents rocky bottoms.

Lymnea fragilis inhabits the prairie [page torn] in very great numbers, I found none in the river to day and I am under the impr[page torn] that I never did find any in it.

Physa heterostropha is exceedingly abundan[page torn] in the prairie sloughs, I do not remember having found it abundant - if at all - in the river I have sometimes found great quantities of this species on the beach about the piers in lake Michigan at Chicago.

I did not find univ cariosus nor u. calceolus as common as usual, in the river to day. u. cariosus is abundant in some small lakes (Crystal Lake &c ^{Crystal lake Illinois - not Crystal Lake in Wisconsin, from when)} near here whose only [illegible] I also have this shell is in high water when they run ^empty into [page torn] I mention these species because I do not see them[page torn] in catalogues of Illinois shells.

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