Born in Lincoln County, TN in 1868 and spending most of her childhood in Blount County, AL - daughter to a wounded Confederate Soldier ( found in the 1880 census ) - her condition was incredibly rare. The tiny body of her twin was only fully developed from the waist down and even then it was malformed – tiny and possessing only three toes on each foot. Myrtle was able to control the limbs of her sister but was unable to use them for walking and she herself had a difficult time getting around as she was born with a clubbed foot. Technically, the ‘Four-Legged Woman’ only had one good, usable leg.

Her father began showing her to curious neighbors for a dime beginning when she was just One Month Old.  This secured her future and provided for the family.  The newspaper ads W. Corbin placed and the national publicity naturally attracted World Famous P. T. Barnum, and at the age of 14 she was signed up for Barnum & London Tours Myrtle was a popular attraction with P. T. Barnum, and later with Ringling Bros. and Coney Island.  

Myrtle was so popular that she was able to earn as much as $450 dollars a week. She retired at age of 18.

At the age of 19 Myrtle married a doctor named Clinton Bicknell.  She had four daughters and a son and it has been rumored that three of her children were born from one set of organs and two from the other. Whether this is true or not; it is medically possible.

Rather than having a parasitic twin, Myrtle's extra legs resulted from an even rarer form of conjoined twining known as dipygus, which gave her two complete bodies from the waist down. She had two small pelvis side-by-side, and each of her smaller inner legs was paired with one of her outer legs. She could move the smaller legs but was unable to use them for walking. 

Account of the Four-Legged Child, J. Myrtle Corbin

Nashville, Tennessee Jun 16, 1868

The undersigned, in response to the request of  a number of physicians, and the relatives and friends of the unfortunate subject of this investigation, give the following testimony: The  infant, J. Myrtle Corbin, has four legs and two distinct external female organs of generation, with two external openings of the urethra  and two external openings of the double rectum.  The external genito-urinary organs are as distinct as if they belonged to two separate  human beings.  The fœces and urine are passed (most generally simultaneously, particularly the urine) from both external urinary and  intestinal openings, situated respectively between the left and right pairs of legs.

The head and trunk are those of a living, well-developed, healthy, active infant of about five weeks, whilst the lower portion of the  body is divided into the members of two distinct individuals, near the junction of the spinal column with the os sacrum.  As far as  our examination could be prosecuted in the living child, we are led to the belief that the lower portion of the spinal column is divided  or cleft, and that there are two pelvic arches supporting the four limbs, which are situated  upon the same plane.

Photographs of this infant have been made by the advice and under the supervision of one of our number.

The reality in this case surpasses expectation, and we are of the opinion that this interesting living monstrosity exceeds in its curious manifestation of the powers of nature in abnormal productions, the celebrated "Siamese Twins."
                                                                                                                                                 Joseph Jones, M.D.,
Prof. of Phys. and Path., University of Nashville.
Paul F Eve, M.D.
Prof. of Surgery, University of Nashville.

The Professors further remark:

Josephine Myrtle is the third offspring of W.H. and Nancy Corban, aged twenty-five and thirty-four, the wife being the senior by nine  years. They are so much alike in appearance, having red hair, blue eyes and very fair complexion, as to produce the impression of their  being blood kin, which, however, is not the case.  Mrs. Corban is from North Alabama, had borne one child to a former husband, the  child having dark coloring, and resembling mostly the father, who had black hair and eyes.  Her three children are all girls; the one  already alluded to , now six years old, another three, and this infant monstrosity, now to be more minutely described, born the  12th of May, 1868, in Lincoln county, Tennessee, five weeks ago.

Mr. Corban is a Georgian, served in the Confederate army through the war, and was severely wounded in the right arm and left  hand.  The parents are in fair health, though the mother is anœmic.  She recollects no fright or disturbance during her last  pregnancy.  The presentation was fortunately the head, which accounts for the preservation of the life of the child.  It would be curious  to speculate on the trouble which might have been produced had the feet or breach presented, while the result, in all probability, would  have proved fatal to the infant, and possibly to the mother.  Mrs. Corban says that there was nothing peculiar in the labor or delivery.   When three weeks old the child weighed ten pounds.  It now nurses healthily, is thriving well, and we saw it urinate simultaneously,  between the two paris of labia of the two vaginæ, situated about six inches apart.  From the crown of the head to the umbilicus the child measures twelve inches, and from this point to the toes of the right and left external feet eleven inches.  From the umbilicus up all is natural and well formed; all below this extraordinary and unnatural.  An inch below the navel is a mark of an  apparent failure for a second one.  There are four distinct, pretty well developed, lower extremities.  They exist in pairs on both sides of  the medium line, which resembles the cleft of an ordinary pair of legs; but here there are no marks whatever of anus or genital organs, and upon pressure we discover no os coccygis or sacrum.  The outer legs of boths sides are the most natural of the  four (though the foot of the right one is clubbed), but are widely separated by the two supernumerary ones, which are less developed,  except at their junction with the body, from which they taper to the feet and toes more diminutive, and which are turned inwards.  One  toe is bifid on the left extra inward extremity.  At birth these extra legs were folded flat upon the abdomen.  We are led to believe that  there are two uteri as well as two recti, in fact, that the pelvic organs are double.  Of course a minute dissection would alone expose the true condition of these parts.

Should this infant reach maturity, and the internal generative organs be double, there is nothing to prevent conception on both sides.   The first difficulty will, however, be in her walking.  The outer, or external, legs may be used for progression; the inner, or inturned,  ones probably never.  These might be successfully amputated at the knee, or higher up.
 

(The Western Journal of Medicine, Theophilus Parvin, ed., 1868)