8. The Tocci boys, born in Turin in 1877. In 1882 they were strong and healthy, and they may be living still. They resembled Rita-Cristina anatomically in every respect. Each boy had control of the leg on his own side, but not of the other leg, consequently they could not walk. Their sensations above the juncture were distinct, and their thoughts and emotions differed.

In the Paris L'union médicale there is an account of a bicephalic still-born monster, born at Alexandria in 1848, which, according to the report, had on one side a typical negro head and on the other side a typical Egyptian fellah head. This report is probably not authentic; but if it is, it would be difficult to reconcile it with the fission theory. [{82}] Supposing the report true, the case would have to be one (1) of superimpregnation wherein (2) a spermatozoon from each source penetrated the same ovum, (3) a bicephalic monster resulted, with (4) distinct racial characteristics. All this is extremely improbable.

Superimpregnation has happened. There are cases where negresses have given birth to twins, one of which was a negro and the other a mulatto. Instances are cited in books on Legal Medicine like those of Tidy and Beck. In Flint's Physiology a case is recorded in which a mulatto woman in Kent County, Virginia, married to a negro, gave birth to twins, in 1867, one of which was a negro much blacker than the mother, and the other a white child, with long, light, silky hair, and a "brilliant complexion." The white child's nose was shaped like the mother's, but there was no other resemblance. Even supposing this to be a case of superimpregnation, that does not fully explain the extreme whiteness of one child and the extreme blackness of the other.

Superfoetation is also possible. Tidy (Legal Medicine) gives a case: "Mary Anne Bigaud, at thirty-seven, on April 30th, 1748, gave birth to a full-term mature boy, which survived its birth two and a half months, and to a second mature child (girl) on September 16th, 1748, which lived for one year." The second child was born four and a half months after the first, and both were "nine-months" children. It was proved after death in this case that the mother had not a double uterus, and the report is vouched for by Professor Eisenman, and by Leriche, surgeon-major of the Strasburg Military Hospital. Several other cases of superfoetation are given by Bonnar (Edin. Med. Journ., January, 1865).

The third genus of Terata Katadidyma is the Ischiopagus. These twins are divided so much from above downward that the heads are at almost opposite ends of the double body. They are joined at the coccyges and sacra, and the spinal columns have nearly the same axis. The trunk organs are complete and separate, except that they are commonly fused in the pelvis. There may be two, three, or four legs, given off at right angles to the pelvis. This kind of monster is not rare. Förster collected twenty cases, and nine new examples [{83}] were reported in the Index Medicus between 1879 and 1893. Ischiopagic twins were born in County Roscommon, Ireland, in 1827, and baptised separately. The Jones Twins, born in Typhon County, Indiana, in 1889, lived for about two years; they were ischiopagi, and they had the very unusual quality, it is said, that they differed in complexion and the colour of eyes and hair. A case was reported in American Medicine, September, 1903.

Classed with the Katadidyma is the genus Pygopagus, although it has four legs. This form is very rare. The twins are joined only by the latero-posterior aspects of the sacra and coccyges, so that the two individuals are placed almost back to back. The trunk organs are independent, except for some fusion near the point of juncture. Examples of this class are the Hungarian Sisters, born at Szony in 1701, who lived to womanhood; the negresses Millie-Christine, born in 1851, and who were recently living in North Carolina; and the Blazek Sisters of Bohemia. The negresses had common sensation in the legs, but Millie could not localise what part of Christine's legs was touched, and vice versa.

The second group of the double autositic monsters are Terata Anadidyma—terata divided from below upward. The first genus is the Dipygus. This has a single body above, but a double pelvis with double lower extremities in the typical cases. There is an exact description of a double monster of this kind in the Gaelic Annals of the Four Masters as early as the year 727 of this era. The chronicler says in that year on Dalkey Island near Dublin, "There was a cow seen which had one head and one body as far as her shoulders, two bodies from her shoulders hindward, and two tails. She had eight legs, and she was milked three times a day."

A perfect human Dipygus with two equally developed pairs of legs is unknown. Catherine Kaufmann, who was born in 1876, and who died in 1878, had a double pelvis with double pelvic organs in part, but she had only one pair of legs. There is a similar anomaly said to be living in Philadelphia at present. Blanche Dumas, born in 1860, had a double pelvis, double pelvic organs, and three legs. Mrs. B., born in 1868, [{84}] had four legs—the two inner ones were smaller than the outer pair. Her spinal column was divided up to the third lumbar vertebra. Her double pelvic organs acted independently. There are living male examples of this form of monster.

The next genus is the Syncephalus, called also Janus and Janiceps. Its lower body is double up to the umbilicus, the trunk single above that point; the head shows signs of doubling, and there are four legs and four arms; the bodies grow front to front. The head usually is large, therefore this monster is born dead.

Another genus is the Craniopagus—twins joined only by the skull or scalp. There are three species, named from the place of union—Craniopagus Frontalis, C. Parietalis, and C. Occipitalis.