I feel fairly certain that the correct birthdate for Mary Ermine Frogg is before 1840. The 1850 enumeration suggests a DOB of 1838; the 1860 census suggests 1839; the 1880 suggests 1838; and the 1900 enumeration gives the DOB as Dec 1839. (The Autobiography of AB Wright also gives 25 Dec 1839.)Of course, the censuses are often off a little, but all 4 of these over a period of 60 years place the DOB before 1840.
Assuming then that Mary Ermine is Arthur's daughter, we would expect to find her with him in the 1840 census. He is still in Tippecanoe Co, IN, but the enumeration there includes only 2 females, both over 15 years old.
Actually Luvisa Smith was already 27 when she and Arthur married in Apr 1841, so it wouldn't be surprising to find that she already had a child. So, I am thinking that mary Ermine's father was either an earlier husband of Luvisa's or perhaps a tiny indiscretion.
At any rate, Arthur apparently raised Mary Ermine as his own -- according to one source, Cornelius, son of Arthur's brother John (d. 1803), was also raised by his uncle Arthur. Sounds like Arthur had a big heart.
I have the same children for Arthur and Luvisa except for Cyril Cornelius. He must have been born about 1855? but he doesn't appear in the 1860 enumeration for Luvisa. Did he die as a child?