20_.--
General Cass, who had been written to, thus expresses himself on this
subject:--

"Captain Douglass has informed me that you and he meditate a joint work,
which shall comprise those objects, literary and scientific, which could
not properly find a place in a diurnal narrative. At what time is this
work to appear, and what are its plan and objects? My observations and
inquiries respecting the Indians will lead me much further than I
intended or expected. If I can prepare anything upon that subject prior
to the appearance of the work, I shall be happy to do it."

_Geological Survey of Dutchess County_.--Dr. Benjamin Allen, of Hyde
Park, writes to me (June 4th) on this subject, urging me to undertake
the survey; but the necessity of closing my engagements in the West
rendered it impossible.

_Expedition of_ 1820.--Dr. Mitchell furnishes me opinions upon some of
the scientific objects collected by me and my associates in the
north-west in 1820:--

"The Squirrel sent by General Cass is a species not heretofore
described, and has been named by Dr. Mitchell the _federation squirrel_,
or _sciurus tredecem striatus_.

"The Pouched Rat, or _mus bursarius_, has been seen but once in Europe.
This was a specimen sent to the British Museum from Canada, and
described by Dr. Shaw. But its existence is rather questioned by
Charles Cuvier.

"Both animals have been described and the descriptions published in the
21st Vol. of the _Medical Repository_ of New York, p. 248 _et seq_. The
specimens are both preserved in my museum. Drawings have been executed
by the distinguished artist Milbert, and forwarded by him at my request
to the administrators of the King's Museum, at Paris, of which he is a
corresponding member. My descriptions accompany them. The originals are
retained as too valuable to be sent out of the country.

"The Paddle Fish is the _spatularia_ of Shaw and _polyodon_ of Lacepede.
It lives in the Mississippi only, and the skeleton, though incomplete,
is better than any other person here possesses. It is carefully
preserved in my collection.

"The Serpent is a species of the Linnaean genus Anguis, the _orveto_ of
the French, and the _blind worm_ of the English. The loss of the tail of
this fragile creature may render an opinion a little dubious, but it is
supposed to be an _ophias aureus_ of Dandin, corresponding to the Anguis
ventralis of Linn, figured by Catesby.

"The shells afford a rich amount of undescrib